WIP: Ordination

A few improvements in ordination:
- Fixing a bug when computing residual site scores in CCA
- Many tests (coverage is now at ~100%, so unlikely that more bugs are hiding in a dark corner)
- Removing the asserts we talked about in the first review because I found a real life dataset where one of them failed for no good reason. `vegan` in R doesn't fail, so we'd better not.
- Reformatting some data files

I have no idea why tests are failing in travis (they pass locally, one of the failures is unrelated) so this is a WIP.