Key view loop fixes/improvements

- Removed unnecessary code at beginning of CPTextField -becomeFirstResponder that might have been a hack to get around a bug I fixed.
- Fixed race condition in setTimeout closure in CPTextField -becomeFirstResponder.
- CPWindow -setInitialFirstResponder now works reliably and follows Cocoa behavior in that if -makeFirstResponder is called with something other than the window before the window is first shown, it will override the initial first responder.
- Like Cocoa, until the first responder is set during window load, the first responder is the window by default, not the content view.
- Optimized search for any view that has a previous/next key view set.
- Sheets can become key windows again.
- CPWindow -recalculateKeyViewLoop now just marks the loop as dirty, per Cocoa docs.
- CPWindow -autorecalculatesKeyViewLoop now behaves per Cocoa, it only has an effect when views are added or removed.
- If the first responder does not have a valid previous/next key view, it does not resign to nil, per Cocoa behavior.
- Code optimization and cleanup.
- Test app (KeyViewLoopTest) that demonstrates various scenarios.

Tests/Manual/KeyViewLoopTest/AppController.j

@@ -0,0 +1,44 @@
+/*
+ * AppController.j
+ * KeyViewLoopTest
+ *
+ * Created by You on January 7, 2013.
+ * Copyright 2013, Your Company All rights reserved.
+ */
+
+@import <Foundation/CPObject.j>
+
+
+@implementation AppController : CPObject
+{
+    @outlet CPWindow customNoInitial;
+}
+
+- (void)applicationDidFinishLaunching:(CPNotification)aNotification
+{
+    [customNoInitial makeKeyAndOrderFront:self];
+}
+
+@end
+
+
+@implementation MyWindow : CPWindow
+
+- (@action)addField:(id)sender
+{
+    var field = [CPTextField textFieldWithStringValue:@"" placeholder:@"" width:96];
+
+    [field setFrameOrigin:CGPointMake(43, 135)];
+    [[self contentView] addSubview:field];
+
+    [sender setEnabled:NO];
+    [self makeFirstResponder:[[self contentView] viewWithTag:1]];
+}
+
+- (@action)recalc:(id)sender
+{
+    [self recalculateKeyViewLoop];
+    [self makeFirstResponder:[[self contentView] viewWithTag:1]];
+}
+
+@end