Add wavemap

[victorreijgwart]

This pull request proposes to add wavemap to the list of SLAM packages. The library performs multi-resolution occupancy mapping in a similar fashion to OctoMap while being more memory efficient thanks to wavelet compression and orders of magnitude faster thanks to a coarse-to-fine measurement integration scheme, multi-threading, and advanced data structures. Compared to our previous work, voxblox, wavemap achieves higher memory efficiency and recall while being equally fast for LiDARs and up to an order of magnitude faster for depth cameras.