Don't marshal Form instance to Lua

[YoshiRulz]

BizHawk/src/BizHawk.Client.EmuHawk/tools/Lua/LuaLibraries.cs

Lines 94 to 99 in c50a4f4

	guiLib.CreateLuaCanvasCallback = (width, height, x, y) =>
	{
	var canvas = new LuaCanvas(EmulationLuaLibrary, width, height, x, y, _th, LogToLuaConsole);
	canvas.Show();
	return _th.ObjectToTable(canvas);
	};

Create a new object with just the published list of callbacks. Maybe some common Form/Control props if people have been using those in the wild.