add Spotscale orthophoto/textured mesh additions

So, this is a monstrous pull request. I should have been explicit in that this should have been done in repo, so my sincere apologies for the oversight.

None-the-less, this is some awesome work by Ludvig Emgard's Spotscale team, including Martin Svensson, Joakim Lindblad, Victor Johansson. This adds meshing, texturing, georeferencing, and orthorectification to OpenDroneMap. I have not finished my review of this (still running a test dataset through), but want to get this elevated to everyone's attention to test.

![langley_screen](https://cloud.githubusercontent.com/assets/1174901/5534040/bdf5e1d6-8a23-11e4-9880-0d8bef77496b.jpg)

![seneca_screen](https://cloud.githubusercontent.com/assets/1174901/5534043/c0f6c7b0-8a23-11e4-90c2-b685a592c666.jpg)

![odm_orthphoto](https://cloud.githubusercontent.com/assets/1174901/5534044/c277d43a-8a23-11e4-85be-89742bb3cc2c.png)

This can be tested with the Seneca dataset: https://github.com/OpenDroneMap/odm_data or any drone image dataset with 80%+ overlap and geographic position in the exif ephemeris.