v0.5.1

 - Fixed bug in GCP triangulation

v0.5.0

 - C++ camera models
 - Analytical derivatives
 - Clang compilation
 - Ubuntu 20.04 (python3), Ubuntu 19.10 (python2)
 - COLMAP import

chore: bump version

chore: bump minor version

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