Add toggle for user interface display

- "/" toggles UI (incl. stats if displayed); menu View > User Interface
- "%" = toggle status; menu View > Stats
- Acts on normal, 3DTV, and Oculus display.
Fixed performance timer scope
Resize the overlay framebuffer when the application window is resized
adding "export QT_CMAKE_PREFIX_PATH=/usr/local/opt/qt5/lib/cmake" for qt5.2.1
adding "export QT_CMAKE_PREFIX_PATH=/usr/local/Cellar/qt5/5.2.1/lib/cmake" for qt5.2.1
Fix for streaming error.
Change tests to reflect transmission changes and fixed issue with reprocessing
already-handled reliable delta.
Timing fix.
Another improvement to clapping to match animation pace with keystrokes
Use congestion control on server.
Use congestion control for client sends, too.
Merge branch 'master' of https://github.com/highfidelity/hifi into metavoxels
Merge branch 'master' of https://github.com/worklist/hifi
switched to better sounds for clapping
Guard _framebufferObject deletion
Integrate UI toggling menu item and Hydra UI toggling

They work together and both fade the UI in / out.
Merge pull request #3142 from mpursley/master

adding "export QT_CMAKE_PREFIX_PATH=/usr/local/Cellar/qt5/5.2.1/lib/cmake" for qt5.2.1
Merge pull request #3141 from ey6es/metavoxels

Fixes, congestion control for metavoxel streaming.
Merge pull request #3139 from PhilipRosedale/master

Another improvement to clapping to match animation pace with keystrokes
Hand low velocity filter as a menu option