Added simple additive/blur-with-persist glow modes, means to cycle through
modes.
Merge branch 'master' of https://github.com/worklist/hifi into glow
Diffuse/add glow mode.
Merge branch 'master' of https://github.com/worklist/hifi into glow
Doxygen-style comments.
Blur/add should be the default.
Doxygen comment fix.
Don't make the avatars glow; that was just for testing.
Merge pull request #854 from ey6es/glow

Three other glow techniques, with menu option to cycle between them.