Easy skinnable components added. Undocumented.

Working components:
Checkbox, Dialogbox, Inputtext, Label, Nine patchbutton, Radiobutton,
Switch, Tab.
No default theme is shipped in the core.
InputText supports multiline (TextArea)

Merged NinePatch into UIComponent
InputText wrap for singleline. Fix for dialog box.
UI components documented.

NinePatch button vertical align added.
InputText, fixed password field.
Added default skin.

UIComponent, added vertical align.
Label extends UIComponent instead FlxText, makes it able to skin it.
Small fixes and typos.

Vertical align changed "center" to "middle".
Fixed vertical tab placement
FlxTabGroup vertical divider graphic packed.
Merge remote-tracking branch 'origin/UI'
FlxUI Listener to IEventListener