Add methods and actions for layout classes as well as the abstract classes for NSCollectionViewLayout.

Declarations added to collectionview layout header.

Clean compile for NSCollectionViewLayout abstract class

Add header for NSCollectionViewFlowLayout.h

Add skeleton implementation of NSCollectionViewFlowLayout

Add implementation for simple setter/getter methods.

Correct compilation error with non-clang compilers

Fix compilation issues

Add getter/setter for collectionViewLayout

Skeleton of NSCollectionViewTransitionLayout implementation

Add encoding/decoding for collectionViewLayout key

Make NSCollectionViewGridLayout default if the NSCollectionViewLayoutKey is not set

Add protocols for DataSource and Prefetching for NSCollectionView

Add 10.11 methods to delegate declaration

remove templating from NSCollectionViewDelegate that gcc can't handle.

New delegate methods for NSCollectionViewDelegate to support NSSets of NSIndexPaths and multiple selection.

Reset .travis.yml to the proper version and modify NSCollectionView.h to use forward declarations for both NSPasteboard and NSPasteboardWriting so that we don't explicitly import.

Add declarations for missing methods from 10.11 version of NSCollectionView

Add new methods for 10.11 for moving, deleting and collapsing sections.

Add new methods from 10.11

Add the remaining missing methods as well as delcarations for blocks needed for batch handler and completion handler.

Add skeleton implementations for all new methods

Changes to add new methods to collection view for delegate

Consolidate the registeredClass and registeredNib maps.

Implementation of dataSource related methods

Implment nib loading for NSCollectionViewItem subclasses

Remove uneeded ivars, add categories for override and layout

Minor formatting change

Update categories and organization of code

Add init method to NSCollectionViewFlowLayoutInvalidationContext

Add collectionview layout subclasses

Declarations added to collectionview layout header.

Clean compile for NSCollectionViewLayout abstract class

Add skeleton implementation of NSCollectionViewFlowLayout

Add implementation for simple setter/getter methods.

Correct compilation error with non-clang compilers

Fix compilation issues

Add getter/setter for collectionViewLayout

Add encoding/decoding for collectionViewLayout key

Make NSCollectionViewGridLayout default if the NSCollectionViewLayoutKey is not set

Add protocols for DataSource and Prefetching for NSCollectionView

New delegate methods for NSCollectionViewDelegate to support NSSets of NSIndexPaths and multiple selection.

Reset .travis.yml to the proper version and modify NSCollectionView.h to use forward declarations for both NSPasteboard and NSPasteboardWriting so that we don't explicitly import.

Add declarations for missing methods from 10.11 version of NSCollectionView

Add new methods for 10.11 for moving, deleting and collapsing sections.

Add new methods from 10.11

Changes to add new methods to collection view for delegate

Consolidate the registeredClass and registeredNib maps.

Add init method to NSCollectionViewFlowLayoutInvalidationContext

Fix issues with rebase

Headers/AppKit/NSCollectionViewFlowLayout.h

@@ -25,15 +25,115 @@
 #ifndef _NSCollectionViewFlowLayout_h_GNUSTEP_GUI_INCLUDE
 #define _NSCollectionViewFlowLayout_h_GNUSTEP_GUI_INCLUDE
 
+#import <AppKit/NSCollectionView.h>
 #import <AppKit/NSCollectionViewLayout.h>
 
-#if OS_API_VERSION(MAC_OS_X_VERSION_10_0, GS_API_LATEST)
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_11, GS_API_LATEST)
 
 #if	defined(__cplusplus)
 extern "C" {
 #endif
 
+enum
+{
+ NSCollectionViewScrollDirectionVertical,
+ NSCollectionViewScrollDirectionHorizontal
+};
+typedef NSInteger NSCollectionViewScrollDirection;
+  
+NSCollectionViewSupplementaryElementKind const NSCollectionElementKindSectionHeader;
+NSCollectionViewSupplementaryElementKind const NSCollectionElementKindSectionFooter;
+
+@interface NSCollectionViewFlowLayoutInvalidationContext : NSCollectionViewLayoutInvalidationContext
+{
+  BOOL _invalidateFlowLayoutDelegateMetrics; 
+  BOOL _invalidateFlowLayoutAttributes; 
+}
+
+- (void) setInvalidateFlowLayoutDelegateMetrics: (BOOL)flag;
+- (BOOL) invalidateFlowLayoutDelegateMetrics;
+
+- (void) setInvalidateFlowLayoutAttributes: (BOOL)flag;
+- (BOOL) invalidateFlowLayoutAttributes;
+@end
+
+@protocol NSCollectionViewDelegateFlowLayout <NSCollectionViewDelegate>
+
+- (NSSize) collectionView: (NSCollectionView *)collectionView
+                   layout: (NSCollectionViewLayout*)collectionViewLayout
+   sizeForItemAtIndexPath:(NSIndexPath *)indexPath;
+
+- (NSEdgeInsets)collectionView: (NSCollectionView *)collectionView
+                        layout: (NSCollectionViewLayout*)collectionViewLayout
+        insetForSectionAtIndex: (NSInteger)section;
+  
+- (CGFloat) collectionView: (NSCollectionView *)collectionView
+                    layout: (NSCollectionViewLayout*)collectionViewLayout
+                    minimumLineSpacingForSectionAtIndex: (NSInteger)section;
+  
+- (CGFloat) collectionView: (NSCollectionView *)collectionView
+                    layout: (NSCollectionViewLayout*)collectionViewLayout
+                    minimumInteritemSpacingForSectionAtIndex: (NSInteger)section;
+  
+- (NSSize) collectionView: (NSCollectionView *)collectionView
+                   layout: (NSCollectionViewLayout*)collectionViewLayout
+                   referenceSizeForHeaderInSection: (NSInteger)section;
+  
+- (NSSize) collectionView: (NSCollectionView *)collectionView
+                   layout: (NSCollectionViewLayout*)collectionViewLayout
+                   referenceSizeForFooterInSection:(NSInteger)section;
+
+@end
+
 @interface NSCollectionViewFlowLayout : NSCollectionViewLayout
+{
+  CGFloat _minimumLineSpacing;
+  CGFloat _minimumInteritemSpacing;
+  NSSize _itemSize;
+  NSSize _estimatedItemSize; 
+  NSCollectionViewScrollDirection _scrollDirection;
+  NSSize _headerReferenceSize;
+  NSSize _footerReferenceSize;
+  NSEdgeInsets _sectionInset;
+  BOOL _sectionHeadersPinToVisibleBounds;
+  BOOL _sectionFootersPinToVisibleBounds;
+}
+
+- (CGFloat) minimumLineSpacing;
+- (void) setMinimumLineSpacing: (CGFloat)spacing;
+
+- (CGFloat) minimumInteritemSpacing;
+- (void) setMinimumInteritemSpacing: (CGFloat)spacing;
+  
+- (NSSize) itemSize;
+- (void) setItemSize: (NSSize)itemSize;
+  
+- (NSSize) estimatedItemSize;
+- (void) setEstimatedItemSize: (NSSize)size;
+  
+- (NSCollectionViewScrollDirection) scrollDirection;
+- (void) setScrollDirection: (NSCollectionViewScrollDirection)direction;
+  
+- (NSSize) headerReferenceSize;
+- (void) setHeaderReferenceSize: (NSSize)size;
+  
+- (NSSize) footerReferenceSize;
+- (void) setFooterReferenceSize: (NSSize)size;
+  
+- (NSEdgeInsets) sectionInset;
+- (void) setSectionInset: (NSEdgeInsets)inset;
+  
+- (BOOL) sectionHeadersPinToVisibleBounds;
+- (void) setSectionHeadersPinToVisibleBounds: (BOOL)f;
+
+- (BOOL) sectionFootersPinToVisibleBounds;
+- (void) setSectionFootersPinToVisibleBounds: (BOOL)f;
+
+- (BOOL) sectionAtIndexIsCollapsed: (NSUInteger)sectionIndex;
+
+- (void) collapseSectionAtIndex: (NSUInteger)sectionIndex;
+
+- (void) expandSectionAtIndex: (NSUInteger)sectionIndex;
 
 @end