timob-13796: window refactor.
1. If "ti.android.useLegacyWindow" is enabled in tiapp.xml, it follows old window behavior, including lightweight and heavryweight.
2. Otherwise, all windows are heavyweight.
3. Both heavyweight and lightweight windows use WindowProxy and use TiView to set their view.
4. Add support for activityEnter/ExitAnimation in close().
timob-13796: Provide a default value for windowPixelFormat. Update the anvil tests. Add new anvil tests.
timob-13796: update doc
timob-13796: address comments
timob-13796: address comments
timob-13796: handle width and height properly for HW windows. ignore top/bottom/left/right for HW windows.
timob-13796: update doc
timob-14558: retain the children in the JS side.
timob-13796-3_1_X: Don't use the property "ti.android.useLegacyWindow". Update the doc.
Merge pull request #4474 from pingwang2011/timob-13796-3_1_X

Timob 13796 3 1 x:Android: Implement new window architecture