Experimental Raygui 3.6 Port

Almost all RAYGUIAPI are ported and uses almost identical to original raygui 3.6.

However, the implementation of GuiLoadStyleFromMemory is kinda hacked together, so expect it to not function correctly.

Also, there are visual glitches in GuiTextBox that text cursor may appear in wrong position.

Moving on to port raygui 4.0.