[GenericDepthPlugin] More compatibility (Few UE3 games)

More compatiliby by adding an option 'ZBufClearIndex'. Works really well here.

I haven't added the 'martinsh_ssao.fx' shader (which you'll see refered as 'MSSAO') because it won't work right now. I'll add it tomorrow. It's not the best AO but it's really fast and handy

I might have added project files again. Weird because I always make sure to exclude it. Damn Git !