Cleanup of input handling

-Store changes to aimangle in cl.in_delta now instead of adding directly
into cl.aimangle
Refactor

-Moved FBO functions out of r_vr.c and into r_fbo.c
-Moved LibOVR C++ interface to r_libovr.cpp
-Moved all OVR specific code to r_ovr.c
-Abstract Oculus specific portions from vr_main.c
-Work on identifying OVR specific code in render path
Improvements

-Removed MyGLUperspective in favor of vrPerspective
-Removed unnecessary push/pop matrix for flipping model
-Show RiftQuake2 instead of KMQuake2 on console
-Fix for multiplayer view drifting
-Bring near clip plane in closer
-Tweak HUD depth handling
Performance improvements for VR mode

-Add vr_nosleep to disable all calls to Sleep()
-Removed need to call glGetFloatv every frame to fetch modelview matrix.
Add Quaternion handling functions
Add neck model
-Added cvar vr_neckmodel to enable/disable
-Added cvar vr_neckmodel_forward to set distance between neck and eyes
-Added cvar vr_neckmodel_up to set length of neck
Fixed issues with HUD bouncing near singularities
-Moved HUD bouncing to using expoential moving average of previous locations not delta (fixes singularity issues).
-Moved to using quaternions to allow spherical interpolation for better accuracy.
New aim modes

-vr_aimmode 5 is now equivalent to TF2/HL2 vr_moveaim_mode 2
-vr_aimmode 6 is now equivalent to TF2/HL2 vr_moveaim_mode 3
-vr_aimmode 7 is now equivalent to TF2/HL2 vr_moveaim_mode 4
-vr_aimmode 8 is a fully decoupled aim/view mode
-vr_aimmode_deadzone has been replaced with vr_aimmode_deadzone_yaw and
vr_aimmode_deadzone_pitch
-Dead zone limit is now 360 degrees
Added debug OVR mode

-Disabled by default
-Enable at run-time by adding parameters +set vr_ovr_debug 1 to the
command line
-Forces OVR specific code to always return success
-Mimics an HD Rift Prototype if no Rift is detected
-Returns a zero orientation vector if it is unable to read a sensor
-Never auto enable HUD transparency
Fix for corrupt bloom textures on changing framebuffer size
Change behavior of vr_ovr_scale

-New default value of 0
-Setting vr_ovr_scale to any value less than 1 forces it to use
calculated full-screen scale
-Values between 1.0 and 2.0 will manually set the distortion scale