Implement Bitmap editing

[CPKreu]

Add a class for interacting with the currently open bitmap. Use ExtensionManager.RegisterGlobal() to register a class.
Classes that are gonna be used in lua need to have the [MoonSharpUserData] attribute

The class could look something like this

[MoonSharpUserData]
class LuaBitmapEditor
{
	public void SetPixel(int x, int y, byte r, byte g, byte b, byte a)
	{
		BitmapManager.activeBitmap.SetPixel(x, y, Color.FromArgb(a, r, g, b));
	}
}

On application start, ExtensionManager.RegisterGlobal<LuaBitmapEditor>("Bitmap") has to be called

A lua script would then be able to set a pixel like this

function Test()
	Bitmap.SetPixel(2, 2, 3, 255, 80, 90, 255);
end

Classes for interacting with lua should be put in Models/ExtensionsModule/