Refactors DisplayListTree class

removes item tree. flat displayobject store is sufficient.
Restores selection after update
Adds simple keyboard nav; optimized element creation
Remove duplicate listeners
Prevents default in displaylist's keydown handler
adds wireframe mode
restores display list scroll position
Use getBounds instead of _bbox
Do not clip invalid regions in wireframe mode
getRegion to return getBounds when in wireframe mode

unsure about this, seems to have undesirable side effects (ghost elements appear in wireframe mode). @tobeytailor, help? ;)
Visualize wireframe outline color in display list
Merge pull request #645 from tobeytailor/avm1

AVM1: Combine GotoFrame and subsequent Play or Stop actions.
Add test case
Initial color transform refactoring
Merge pull request #630 from artcompiler/fix618

Add regression test for class initialization
Merge pull request #647 from yurydelendik/cxform-1

Initial color transform refactoring
Fix xl.*, where xl is an XMLList
Merge pull request #649 from artcompiler/e4x

Fix xl.*, where xl is an XMLList
cosmetics
prevent displaylist panel to show unnecessary scrollbar in firefox