Add regression test for presence crossing between regions on the same simulator.

Unlike a much earlier commented out version of this test, this is done in synchronous mode.
Add code for testing event queue messages recevied on region cross.

This is currently disabled pending an improvement in the test code to properly add avatars when an event queue module is present.
Merge branch 'master' of ssh://opensimulator.org/var/git/opensim
minor: remove some completely unused string local vars added recently in commit 984faf2
Fixed inconsistency in comments. Thanks Ai Austin.
Merge branch 'master' of ssh://opensimulator.org/var/git/opensim
One more comment inconsistency fixed.
* Just another one of those new packet blocks causing a null ref.   Defaulting to zero length array.....
* Apparently, sometimes texture entries come in from the wire with no default texture defined..  so apply better fallback protection against that.   The net result is clients will have their selected textures set when they would have previously had an ignored exception.
Merge remote-tracking branch 'upstream/master'