added: PosixFile

this replaces HDFile on posix platforms
fixed: settings depends on ffmpeg
changed: remove unused (Copy|Move|Delete)File from XFileUtils
changed: trim more unused stuff from XFileUtils
changed: trim XFileUtils from linux PlatformInclude

absolutely no reason for pulling in this header everywhere
changed: remove XHandlePublic.h from linux PlatformInclude

no need to pull this header everywhere
changed: remove XTimeUtils from linux PlatformInclude

no reason pulling this header everywhere
changed: remove XMemUtils.h from linux PlatformInclude

no reason to pull this header everywhere
changed: remove ConvUtils from linux PlatformIncludes

no reason for pulling this header everywhere.

PlatformIncludes is finally a dummy wrapping PlatformDefs.h