Add back basic compositor and maybe advanced layers too

[K4sum1]

WebRender has multiple incompatibilities with pre-7. I was able to work around the one issue it had with Vista, however XP if I ever do it has bigger issues.

1: WebRender requires SRW locks
Well not exactly, but it uses multiple read locks or some other features mutex's and critical sections don't support. A solution could be derived by using Semaphore's, however I'm not going to be able to do that. Maybe it will come in next Rust9x release though. For Vista I bypassed this by faking the TryAcquireSRWLock functions with their non-Try counterparts.

2: WebRender requires DWrite.dll
I'm not sure what or where exactly it depends on it, but it has seemingly required it before version 90. Not sure how to test this as I seemingly can't force WebRender to initialize and crash in the older versions where Basic/Layers still exists when DWrite.dll is deleted.