Add machinery for SkyCoord to auto-search tables for appropriate columns
Use unit from Table column
revert SkyCoord initializer back to master
changed to guess_from_table classmethod
Add changelog entry
Fix accidentally left in exception
Fix case of double-specified error and add related tests
typo fix
Adapted @taldcroft's gist to guess_from_table
switch to not having a pluggable function
add RE-based parsing scheme for table names
update guess_from_table tests
Alter docstring a bit to reflect new scheme
Add underscore to regex and associated test
Fix for case of providing coordinate in both keyword and table

mistake pointed out by @taldcroft
Clarify description of parsing
Also match columns that *end* in the attribute name
Use "as" form if pytest.raises instead of try/except
Clarify "non-alphanumeric" definition and make the regex UNICODE
another tweak to explanation of column-matching algorithm