WIP: Implement dxg.sys DxDdEnableDirectDraw

Created an attachment (id=4295)
The actual implementation

Here is an implementation of DxDdEnableDirectDraw in dxg.sys. Next step is to implement DxDdCreateDirectDrawObject.

Some changes were made to the PDEVOBJ structure, to better reflect what windows actually does. See Windows Graphics Programming by Feng Yuan.

Comments are welcomed.

PS: It seems that DxDdEnableDirectDraw fills the DDHALINFO structure too, which seems a safe bet, as there doesn't seem to have a dedicated function in dxg.sys.
Adding it would not be too hard .