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.
