Provide suggestions when an exact unit match can not be found.
Add Returns clause to docstring
Handle unit suggestions by removing accents on Unicode characters,
e.g. ångström -> angstrom.  Fix some other Unicode-related issues.
Remove unused import
Add CHANGES.rst entry
Fix CHANGES.rst
Merge pull request #1870 from mdboom/unit/recommend

Recommend alternatives when a unit isn't found
Update MaskedColumn to fix unicode column names like in Column
Fix u'' syntax, not in python 3.1, 3.2
Merge pull request #1934 from taldcroft/table/fix-masked-col-name

Update MaskedColumn to fix unicode column names like in Column