Add baryonic matter density paramter and its evolution to cosmology classes
add dark matter only density parameter and its evolution
update doctests for Omega_b
Forced rebuild because of merge issues with astropy_helpers

* The commit history where astropy_helpers accidentally got
  modified is making rebasing off of master really messy, so
  rebuilt from current.
* CHANGES.rst not modified, so this is *not* ready to go.
  Should wait on 0.4 to shake out before updating that.
Update CHANGES to include cosmology clone operation

* Placed in 1.0 section
* Closes #2592
Rewrite Distance initializer so it can take lists of quantities.
Put back in automatic unit selector for distmod with array support
Add baryonic matter density paramter and its evolution to cosmology classes
Expand locale known issue
typo fix: arcseconds->milliarcseconds


[ci skip]
Describe bounds checking at toplevel of docs.
add dark matter only density parameter and its evolution
update doctests for Omega_b
Fix formatting error that causes PDF/LaTeX docs to not finish.
Don't put all user documentation under the "what's new" heading in LaTeX docs.
Merge branch 'omega_b' of github.com:joergdietrich/astropy into omega_b
do not raise an exception if Ob0 is accessed and None, return None
Mention Omega_b
Consistent treatmemt of `Ob` and `Odm`

Do not pretend that Ob0 is 0.0 if `Odm0` and `Odm` are accessed and `Odm0` is `None`.
test consistent dark matter, baryonic matter, all non-rel. matter evolution