Support for Windows Transparency

* Added DWM functionality
* Added background clearing
* New switch to package.json
* New Window.isTransparent getter to signal if transparency is enabled
* New window.beginMouseOffclient to trap mouse events offscreen (needed for resizing transparency)
* New Window.endMouseOffclient to end trapping mouse events offscreen (needed for resizing transparency)
Transparency support in Mac OS X
Fixed bug where composition isn't established correctly.
Added webgl support in preferences.
Merge branch 'transparency' of https://github.com/trevorlinton/node-webkit into transparency
Merge pull request #1 from rogerwang/master

Update from base
Merge branch 'master' into transparency

Conflicts:
	src/api/window/window.cc
	src/browser/native_window.cc
	src/browser/native_window_win.cc
Added myself to Authors
Support Snow Leopard Transparency
Merge pull request #439 from trevorlinton/transparency

Transparency Support in Mac OS X/Windows
Merged nw-transparency
Implemented transparency (merged from trevorlinton's Tint)
Merge branch 'master' of https://github.com/rogerwang/node-webkit