EXP-1942, EXP-1945: Improved handling of the maturity preference change response. Still needs work though.

EXP-1942,EXP-1945: Altering behavior when setting maturity preference to check the server response in an effort to ensure the viewer and server remain in sync.  This is a partial commit as I still need to add user behavior and notifications when things go wrong.

EXP-1948: Ensuring that we show the maturity changed notification in the case of a teleport failure on the second attempt.

Removing some code that allowed the viewer to toggle the user's maturity access level.  But only toggling it in the viewer leads to some really bad discontinuities with the server's actual access level for the user.

EXP-1944: Changing the default answer for the LandClaimAccessBlocked_Change and LandBuyAccessBlocked_Change notifications.

EXP1-1945: Adding in a flow to catch other cases of teleportation failures due to maturity levels and bad network access.  Still need better copy for the error message.

EXP-1941: Adding in debug setting to force enable purchase flow disregarding other checks including maturity.

EXP-1928: Restoring the flow for non-teleport-failure messages through the special notification handler.

EXP-1940: BUGFIX Correcting issue with changing maturity setting and teleporting from dialog did not work on agni.  Problem stemmed from 2 issues.  1) The server responded with different results between aditi and agni due to some changes in the Pathfinding project.  2) The viewer was actually sending two separate requests to change to the same preference setting.  This fixes both issues.

EPX-1938: Adding a special behavior for the NotAgeVerified notification to display either an ignorable modal dialog or a toast-style notification.  Also, altering the copy for the notifications.

EXP-1928: Constructing the new maturity preferences flow for the case of a teleport via lure (which cannot be restared).

EXP-1928: Handling the rare case that the user preferences cannot be successfully changed, and reporting that to the user.

EXP-1928: Adding functionality to show either a modal notification dialog or the toast-style notification if a teleport fails due to maturity preferences.

EXP-1928: Removing ability to restart a teleport via lure because the re-attempt will fail on the server.

EXP-1928: First pass at building the functionality to restart teleport after increasing the maturity preference level to match the intended teleport region.  There are probably still some cases that are broken and bugs.

EXP-1928: Adding fundamentals for managing a teleport request in such a way that it can be restarted.

Notification handlers now use LLHandles to screen channels.

Fixed boost trackable objects usage.

As far as I can tell, if login fails with the "Region has begun the logout process" message, gAgentAvatarp gets destroyed, which leads to the crash.
Adding a check that should prevent it (could not reproduce to make sure).