added GSdoc comments to class, method, and function declarations; for some classes some comments were already in the source file (not the header), in which case further comments were added here; otherwise comments were put in the headers

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@19588 72102866-910b-0410-8b05-ffd578937521

Source/NSTimer.m

@@ -36,6 +36,14 @@
 @class	NSGDate;
 static Class	NSDate_class;
 
+/**
+ * An <code>NSTimer</code> provides a way to send a message at some time in
+ * the future, possibly repeating every time a fixed interval has passed. To
+ * use a timer, you can either create one that will automatically be added to
+ * the run loop in the current thread (using the -addTimer:forMode: method),
+ * or you can create it without adding it then add it to an [NSRunLoop]
+ * explicitly later.
+ */
 @implementation NSTimer
 
 + (void) initialize