I've been working for around a month on that level editor, and I dont find the time anymore to complete it.
So here it is, there's some resources that can be used and there's some others that doesnt work
Some feature can be done more efficiently like avoiding the use of SetPixel to render 8x8 tiles or the lazy VRAM class
Use it for your project, complete it or do what you want! (An open source project would be great...)