Merge latest viewer-hotfix, approximately equal to Viewer 2.0 final

doc/contributions.txt

indra/llaudio/llaudioengine.cpp

indra/llcommon/llcursortypes.cpp

indra/llcommon/llcursortypes.h

indra/llcommon/llsys.cpp

indra/llcommon/llsys.h

indra/llcommon/llworkerthread.cpp

indra/llimage/llimage.cpp

indra/llmessage/llinstantmessage.cpp

indra/llmessage/llinstantmessage.h

indra/llmessage/lltemplatemessagebuilder.cpp

indra/llmessage/lltemplatemessagereader.cpp

indra/llplugin/llpluginclassmedia.cpp

indra/llplugin/llpluginclassmedia.h

indra/llplugin/llpluginprocesschild.cpp

indra/llplugin/llpluginprocesschild.h

indra/llplugin/llpluginprocessparent.cpp

indra/llplugin/llpluginprocessparent.h

indra/llrender/llfontgl.cpp

indra/llrender/llfontregistry.cpp