Audio engine changes:

-Idle tick is now responsible for dispatching all pending sound sources, as such improves priority sorting.
-Added ui sound precache mechanisms (to fetch sounds without associated soundsources)
-Audio engine no logner available pre-login or upon disconnect, for simplicity.
-General cleanup to the audio engine/impl.
-Fixed some gAudiop calls that were lacking prerequisite null checks.
-Added 'isUpstreamOK' procuedure to LLAssetStorage to allow avoidance of making requests when there is no upstream host connection.

indra/newview/llfloaterblacklist.cpp

@@ -174,7 +174,8 @@ void LLFloaterBlacklist::addEntry(LLUUID key, LLSD data)
 				std::string wav_path= gDirUtilp->getExpandedFilename(LL_PATH_CACHE,sound_id.asString()) + ".dsf";
 				if(LLAPRFile::isExist(wav_path, LL_APR_RPB))
 					LLAPRFile::remove(wav_path);
-				gAudiop->removeAudioData(sound_id);
+				if(gAudiop)
+					gAudiop->removeAudioData(sound_id);
 			}
 			blacklist_entries.insert(std::pair<LLUUID,LLSD>(key,data));
 			updateBlacklists();