Update/Modernize LLAvatarName and LLAvatarNameCache and _EVERYTHING_ they touch

Fairly certain this adds the feature in which the user may click the online notification to open a chat with the user coming online.

Translators may want to look at the xml changes of this change to see what to update

Removes old LegacyMultiAttachmentSupport patch
Moves LLAvatarName-centric functions into LLAvatarName from elsewhere.
Adds boost::signals2::connections to name polling places.
Removes more old icky static callbacks
Merge from Alchemy, credit where due~
Update notifications.xml to have a bunch of the tags from upstream to ease diffing

indra/llmessage/aihttptimeoutpolicy.cpp

@@ -907,7 +907,6 @@ AIHTTPTimeoutPolicy const* AIHTTPTimeoutPolicy::getTimeoutPolicyByName(std::stri
 // Policy name									Policy
 P(assetReportHandler);
 P(authHandler);
-P(avatarNameResponder);
 P2(baseCapabilitiesComplete,					transfer_18s_connect_5s);
 P(blockingLLSDPost);
 P(blockingLLSDGet);
@@ -926,8 +925,6 @@ P(fetchScriptLimitsRegionSummaryResponder);
 P(fnPtrResponder);
 P(floaterPermsResponder);
 P2(gamingDataReceived,							transfer_22s_connect_10s);
-P(groupBanDataResponder);
-P2(groupMemberDataResponder,					transfer_300s);
 P2(groupProposalBallotResponder,				transfer_300s);
 P(homeLocationResponder);
 P2(HTTPGetResponder,							reply_15s);
@@ -962,14 +959,11 @@ P(startConferenceChatResponder);
 P2(startGroupVoteResponder,						transfer_300s);
 P(translationReceiver);
 P(uploadModelPremissionsResponder);
-P(userReportResponder);
 P(verifiedDestinationResponder);
 P(viewerChatterBoxInvitationAcceptResponder);
 P(viewerMediaOpenIDResponder);
 P(viewerMediaWebProfileResponder);
 P(viewerStatsResponder);
-P(vivoxVoiceAccountProvisionResponder);
-P(vivoxVoiceClientCapResponder);
 P(voiceCallCapResponder);
 P(webProfileResponders);
 P(wholeModelFeeResponder);