Mats UI.

Includes Chalice Yao's pause agent on attachment selection in LLSelectMgr::updateSelectionCenter()
Includes some of Cinder Roxley's enhancements to the build floater for materials (flip buttons, sync materials, consistent control hiding)
Includes Ansariel Hiller's fix for FIRE-8298 [BUG-869] [MAINT-1961], since this updates lltexturectrl.* to have related behaviors.
Switches from using MIN_MANHATTAN_DIST for threshold in LLToolDragAndDrop to using the existing DragAndDropDistanceThreshold debug, like upstream.

Translators:
panel_tools_texture.xml should now be translated, floater_tools.xml should have the old panel removed.
strings.xml now has "use_texture" string.
notifications.xml Now has "LivePreviewUnavailable" alert. (don't forget to translate the ignoretext)
Don't open disabled submenus!
ContextMenu Support!

LLContextMenu functionality pulled out of LLPieMenu, PieMenu is now derived from LLContextMenu
- The more attribute boolean of pie_menu element determines whether or not to have an actual submenu if it's not a pie, defaults to false which means actual submenu..
-- in the future we may want to have more more="true" depending on feedback
- Pie menu labels now dynamically get " >" appended to them (avoids stupid looking context menus)
- Positioning logic combined in part, mostly conditional still, in the future we could probably combine it more.
- handleHoverOver function combines common functionality between context and pies given an item and hover mouse coords.

LiruUseContextMenus debug setting determines which to use, default is pie, of course
- Context(/Pie) Menus are rebuilt when the setting changes value
-- this is safe at any point because all startup states have been accounted for
- "Use context menus instead of pie menus" added to System->General preferences (it's close to the bottom)