merge Branch_1-19-1-Viewer -r 80930 : 81609 -> release

DEV-11202: Unhandled Excpetion in pipeline.cpp.
Merged over updated windlight ui help text from windlight14.
Reverting a const change in a virtual that was not propagated to all overrides.
DEV-10957 stop and pause Media and music buttons do not work
DEV-10762 Displayed page in the client browser disappears when crossing property boundaries.
DEV-11220 replace misspellings in alerts.xml parameters of 'messsage'
DEV-11221 fix a misspelling of 'participants' in floater_chat_history.xml tooltip
DEV-11193 clean up some viewer strings related to Windlight help text
svn merge -r81144:81147 svn+ssh://svn/svn/linden/branches/1-19-1-viewer-threads
DEV-11110  	 Media browser history dropdown does not save items across sessions
Ran the xuiparse -process tool on all en-us xml files.  This does NOT change any data, merely reorders attributes and cleans up tab/spacing.
DEV-11349 XML CLEANUP: fix duplicate sibling names in en-us xui files
DEV-11348 Change to llmimetypes.cpp broke Media Type dropdown
dev-10623 "parcels that played movies no longer work in combo-merge-ui"
DEV-11379 - crash in LLTabContainer::draw()
DEV-11377 Elminiate dangerous LLLinkedList and LLDoubleLinkedList from newview
DEV-11158 sculpties on the top10 crash list
DEV-11404 "Send Current URL to Parcel" does not set the MIME type
merge 80958:80959 maint-ui-9-qa, DEV-11105 -- Searching for people with 3 characters like "j l" hurts the database.
DEV-10489: no draw distance cheating
DEV-879: water noise frequency
DEV-10764: macbook air support
DEV-10878: Linux Intel945 support
DEV-7551: featuretable adjustments for framerate.
DEV-11426 Enormous mini-map.
DEV-11505 - Crash in gunzip_file.
Removed final LinkedList, SkipMap, and AssocList templates from the Viewer!
DEV-11115  truncated word in the Advanced Water Editor's modal help dialog