Refactor dials_regression so it can be made public

[phyy-nx]

dials_regression is currently an svn repository with code, data for regression tests, and publication notes. Since it is hosted on cci.lbl.gov, if a user wants to run the dials_regression tests, they need an account at LBL. I propose getting it ready for public distribution thusly:

• 1. Move the doc folder into new repository. Presumably still svn, and we are happy to host it at lbl. Idea is that the notes, docs and in-process publication tex files are better served living in a separate location from the test data. Proposed names: dials_doc, dials_intranet, dials_notes, or something similar.
• 2. Move python code that's run by the nightly tests into dials and dxtbx proper. There are only 3 tests in run_tests.py anyways.

With these two changes, dials_regression will be a bucket of test data that we can zip it up and host for public downloads like xia2_regression, without worrying about distributing raw notes and extraneous code.

Thoughts? I'm happy to set this up, and I would do my best to preserve commit histories, if possible.

[graeme-winter]

100% behind this - since @Anthchirp did this for xia2_regression already may have thoughts?

[dagewa]

I think all relevant tests are now in DIALS or dxtbx. There is still a lot of material in doc/ though