math: Clean code in HomographyFunctor

There was an absurd amount of std containers being allocated here. I
think young Zack did all this.
plate2kml: Minor wording change
CameraBBox: Speed up by a factor of 20 per Zack

- Change the cost function when intersecting a DEM with a ray to avoid projecting into the camera which is expensive.

- Also consolidate some code I duplicated earlier.

- All tests are passing