Merge branch 'DRTVWR-588-maint-W' into marchcat/588-w-pbr-merge
# Conflicts:
# indra/llrender/llgl.cpp
# indra/llrender/llvertexbuffer.cpp
# indra/llui/llflatlistview.cpp
# indra/newview/lldrawpoolground.cpp
# indra/newview/llspatialpartition.cpp
# indra/newview/lltexturefetch.cpp
# indra/newview/llviewergenericmessage.cpp
# indra/newview/llviewertexture.cpp
# indra/newview/llvosky.cpp
# indra/newview/skins/default/xui/en/floater_preferences_graphics_advanced.xml
# indra/newview/skins/default/xui/en/floater_stats.xml
# indra/newview/skins/default/xui/en/floater_texture_fetch_debugger.xml
# indra/newview/skins/default/xui/en/notifications.xml
# indra/newview/skins/default/xui/en/panel_performance_preferences.xml