MP1-4319 : Fix exception when CleanupThumbs() when textures is null.
Merge remote-tracking branch 'remotes/origin/MP1-4319-BUG-Fix_null_exception_in_GUITextureManager.cs'
Revert "Merge remote-tracking branch 'remotes/origin/MP1-4070_BUG_Resuming_from_Standby_not_working'"

This reverts commit b7d978124fea82e11eed1005827cd8684fa5f989, reversing
changes made to 5f3b5d1c7e8f1c5bc9d453043270b726d19059ec.
Merge remote-tracking branch 'remotes/upstream/master' into 1.6.0Fork-BDJ