Fix timer bug with script engine

	Occurs when Script.clearInterval() called inside
Script.setInterval callback
Merge pull request #3440 from ey6es/master

Fix for eyes on skeleton (e.g., Mixamo) models.
Merge pull request #3442 from Atlante45/script_engine_fix

Fix timer bug with script engine
Merge branch 'master' of https://github.com/highfidelity/hifi