Support for an idle render time step.

The basics of this is, if the application has changed its active state
then we only call paintGL every N milliseconds.  Currently the default
time step is 100 milliseconds.
Use QApplication::applicationState to detect if we're in the background.

May want to expand upon this at some point; if we’re hidden we most
definitely *do not* want to render anything
Use the applicationStateChanged signal.
Refactor if..else into a switch.

Also support the hidden and suspended states.
Skip rendering when we're minimized.
Merge branch 'master' of https://github.com/Geenz/hifi into 19514
Merge branch 'master' of https://github.com/Geenz/hifi into 19514
Only update the full set of joints when we've received new data from the
mixer.  Closes #2274.
Do a simple frustum check for rendering the avatar or doing a full joint
update.  Closes #2071.
Fix for slight graphical glitches on loading avatars.
Visage toggle bits.
Tweak to Visage toggle.
Tweak in code styling per Brad’s feedback, along with using SIGNAL and SLOT instead of function pointers directly.
Merge branch 'master' of https://github.com/Geenz/hifi into 19514
Changed the font of the entire chat window to Helvetica/Arial.
Indentation!
Moved the chat from a window to a built-in panel.
Wait until we know that Faceshift didn't connect before we attempt to
initialize Visage.
Make sure to stop Visage before deleting it.
Merge pull request #2303 from ddobrev/xmppchat

Moved the chat from a window to a built-in panel