Add expanded anisotropic filtering options

indra/llrender/llgl.cpp

indra/llrender/llgl.h

indra/llrender/llimagegl.cpp

indra/llrender/llimagegl.h

indra/llrender/llrender.cpp

indra/llrender/llrender.h

indra/newview/app_settings/settings.xml

indra/newview/featuretable.txt

indra/newview/featuretable_linux.txt

indra/newview/featuretable_mac.txt

indra/newview/llappviewer.cpp

indra/newview/llfeaturemanager.cpp

indra/newview/llfloaterpreference.cpp

indra/newview/llpresetsmanager.cpp

indra/newview/llviewercontrol.cpp

.../default/xui/en/floater_preferences_graphics_advanced.xml