changed Beta1D and Beta2D to Moffat1D and Moffat2D
added CHANGELOG entry and make some recommended changes with capitalization
Merge pull request #3260 from hamogu/rename-beta1d-and-beta2d-issue-3029

Rename beta1d and beta2d - solves issue 3029 (This takes over #3102)
changed thrown error to TypeError to indicate type mismatch
implemented getter and setter for format to check its validity upon setting
A number of changes in order to get this fix working with the current
Column implementation in master.  This also made a few changes to
methods like __array_finalize__ and __setstate__ to not go through the
setters for name, unit, and format--these are copying/recreating
Columns from existing objects that should presumably already have valid
values for those attributes.

This also addresses my comment on the original PR here:
https://github.com/astropy/astropy/pull/3055#discussion_r22355484

Finally, in order for this to pass testing several existing tests needed
to be updated, now that we no longer allow a Column with an invalid
format to be created in the first place (a change I support).