fix: keep vector_angle for single vector pairs.

fix(undistort): make perspective views of panos the same size as the …

…depthmaps

Use pointers for return values.

Compute and clean depthmaps in parallel

Merge pull request mapillary#105 from spikeheap/patch-1

Adds eigen dependency to Readme for OSX

Ignore matching_gps_neighbors if any image has no GPS data