fix bug preventing butterflies from animating

(forgot to make base method virtual)
add DIRTY_UPDATEABLE flag for changes that need it
Merge pull request #3925 from AndrewMeadows/thermonuclear

fix for non-animating models
Reduce the MTU size to deal with Windows networking issue.
Merge pull request #3926 from ey6es/master

Reduce the MTU size to deal with Windows networking issue.
Merge branch 'master' of https://github.com/highfidelity/hifi into mouse_pick_in_oculus