resample or reproject?

Currently the repo is called `reproject`, but the folder is called `docs/resample` ... they should be made consistent.

@astrofrog As I've said before I would prefer the term `resample` and to include e.g. `downsample` and `upsample` methods here, but if I understood correctly you prefer not to put those here and call it `reproject`, right?
Should I attach a commit here that renames `docs/resample` to `docs/reproject`?