MAINT-6631 - reluctantly, added support for animation of collision volumes, to avoid breaking existing content.

SL-109 - made viewer much less tolerant of bad data in avatar_skeleton.xml or avatar_lad.xml. If either of these is broken, there's no point trying to continue, more informative to just error out with an appropriate message.

SL-433 - fix for mesh eye scaling with eye size slider. Previous values were based on incorrectly sized reference eyes.

SL-242 - more tweaks around alt eyes and wings. Alt eyes are now parented to face root, and alt eyes animate along with the original eyes inside the LLHeadRotMotion code.

MAINT-6380, SL-399 - vertical flicker related to joint offsets for mPelvis. Having a joint offset for mPelvis is still a bad idea, but it won't cause as much flickering now.

SL-276 - small skeleton file tweaks to 'end' and 'connected' attributes (no functional impact on viewer)

MAINT-6484 - make the attachment pos updates a bit smarter, so we don't flag the pelvis has having changed unless it has actually changed. Avoid excess calls to computeBodySize(), which can cause a vertical position glitch.