Add VR display auto-calibration logic
Add VR display auto-calibration user message calculations
Make overlays accessible from C++ code
Add some property setters to the billboard overlay
Display a static billboard prompting user to hold still to calibrate HMD
Fix avatar rotation erroneously initiating HMD calibration
Delete calibration message if exit VR display while calibrating
Fix header declaration
Make calibration message update its location more often
Working on ray/voxel intersection testing.
fix for delete of object table row
remove some extra console logs
Merge pull request #3577 from birarda/master

fix for delete of object table row
add boundBox gettable property to EntityItemProperties
draw selection handles for bounding box correctly when rotated
Update SVG file location
Use const parameters
Use NULL rather than 0 for "no overlay"
Merge pull request #3580 from ZappoMan/editToolsImprovements

better handling of rotated entities
Tidy up log messages