Prior to this change when using CloneTool on a transparent background
the output was a solid black brush stroke. Now it is based on the
source content alpha as well as it's color blended with the target.
Gfx::Color is always 4 bytes (it's just a wrapper over u32) it's less
work just to pass the color directly.
This also updates IPCCompiler to prevent from generating
Gfx::Color const &, which makes replacement easier.
Previously, all keydown KeyEvents were accepted, causing parent widgets
not to receive them. With the addition of shortcut handling to keydown,
shortcuts were not called when the ImageEditor was focused.
