Implement acceptsFirstMouse so to return YES, otherwise tablees in new windows do not get mouse selection events. (#173)

Seems to match Apple's implementation.

Source/NSTableView.m

@@ -3568,6 +3568,11 @@ static inline NSTimeInterval computePeriod(NSPoint mouseLocationWin,
   return NO;
 }
 
+- (BOOL) acceptsFirstMouse: (NSEvent *)theEvent
+{
+  return YES;
+}
+
 - (void) mouseDown: (NSEvent *)theEvent
 {
   NSPoint initialLocation = [theEvent locationInWindow];