Finish wrap panel

[BobDickinson]

WrapPanel is pretty much there. Address issues below:

Win\WinPhone - custom WrapPanel imlementation

• Item alignment (always top/left now)

Android - based on FlowLayout

• Needs margin-based layout
• Needs fixed size support
• Item alignment (gravity)?

iOS - uses UICollectionViewFlowLayout

• Needs fixed size support
• Items always aligned center (opposite orientation) and rows/cols justified. We'd have to implement our own custom layout to change that. That being said, we can still align items within the fixed size (I think).

Win/WinPhone/Android

• Auto-scrolling in overflow dimension (iOS does this now). Not totally sure about this (probably makes more sense for a data-bound "view" version of this control).

[BobDickinson]

Android - Completely fixed (margin-based layout, item gravity based on item alignment, and fixed cell size support).

iOS - The full justification issue is fixed.

Still need item alignment on iOS and Windows Still need fixed size support on iOS (though not a high priority)

[BobDickinson]

Verified that Windows/WinPhone already had alignment support.

Added fixed size support and item alignment support to iOS.

All platforms now feature complete.