Removed FlashDevelop project file

We don't want IDE files included in the repro.
Added clear() calls to GraphicsAPI example

This is so the example tests a more realistic per-frame clear/draw
cycle. Helps to expose memory leaks.
Graphics.as class refactor

Fixes memory leaks caused by undisposed fills.

Also fixes a number of other problems where fill style settings weren't
being applied to primitive shapes.

beginBitmapFill() has been dropped from the API in favour of
beginTextureFill(). Automatically creating textures from bitmaps within
the API was a prime cause of monster memory growth when used unwisely,
and building a system to manage this introduces lots of complexity.
Better to force the user to manage their own textures (which, frankly
they should be doing carefully anyway with GPU code).