refactoring
Some refactoring and increased test coverage
added toolbar tests
refactoring and created a triangle tool.
introduced BitmapDrawer.as to seperate the task of knowing where to draw a circle from the task of knowing how to draw that circle in BrushTool.as
Added extra layer of abstraction for the brush tool.

BrushTool now delegates drawing the bitmap to a BitmapDrawer object, it's only job now is deciding where to draw the bitmaps.
Merge branch 'refactoring' into development