SH-477 Better mesh streaming cost estimation.

indra/llcommon/llsdserialize.cpp

indra/llprimitive/llmodel.cpp

indra/llprimitive/llmodel.h

indra/newview/app_settings/settings.xml

indra/newview/llfloatermodelpreview.cpp

indra/newview/llmeshrepository.cpp

indra/newview/llmeshrepository.h

indra/newview/llselectmgr.cpp

indra/newview/llselectmgr.h

indra/newview/llviewerobject.cpp

indra/newview/llviewerobject.h

indra/newview/llviewerwindow.cpp

indra/newview/llvovolume.cpp

indra/newview/llvovolume.h