These casts should fix the warnings on OS X.
Merge pull request #730 from ey6es/master

These casts should fix the warnings on OS X.
Merge branch 'master' of https://github.com/worklist/hifi into pointy
Use only valid values to compute mean, and use the post-warp data to avoid
breaking on head tilt (because we were using the bounds of the rotated rect,
which included too much background).
Ignore maximum values when computing the depth.