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
Import units on top so u.day, etc., can be used throughout
Squashed commits for masked column pattern change

  Make our MaskedColumn like the example in numpy.ma.tests.test_ma.MSubArray
  Updated implementation; Passes all but 2 tests
  Move most Column stuff into BaseColumn
  Add option to allow converting MaskedColumn to Column in BaseColumn
  Copy mask and change so mask len must match array len
  Add Column.__new__ which mostly calls BaseColumn.__new__, and some cleanup
  Strip off the BaseColumn-ness for repr and str to fix MaskedColumn repr
  Rewrite copy so it works for both Column and MaskedColumn
  Need to adjust fill_value in MaskedColumn.copy
  Remove unnecessary BaseColumn.__str__, MaskedColumn.__array_finalize__
  Further unify copy by making BaseColumn version fully general; improve docstring
  Set fill_value via setter, not MaskedArray constructor
  Residual cleanup from rebase
  Make MaskedColumn inherit from Column to get output methods
  Use six.callable for compatibility with Python 3.1
  Remove a misplaced str() conversion
  Update CHANGES.rst
Replace other use of "u" as variable with "rxy" in TDB calculation
When initing from BaseColumn instance w/o attrs, don't try using those attrs
Add "known issue" for quantities sometimes losing their units
Merge pull request #1872 from taldcroft/table/mask-play

Change the subclassing pattern for MaskedColumn
Merge pull request #1936 from mhvk/time-import-units-on-top

Import units on top so u.day, etc., can be used throughout
Correct UT in calculation of TDB; closes #1938
Also update TDB, TCB in test done in documentation
further changes based on feedback from @eteq
Merge pull request #1939 from mhvk/time-correct-ut-in-tdb

Correct UT in calculation of TDB; closes #1938
Merge pull request #1925 from mhvk/time-delta-ut1-utc

Attempt to calculate delta_ut1_utc when the attribute is accessed directly
Add convenience class for comma-separated-values files

Read and write comma-separated-values files with
ascii.read(‘file.csv’,format=‘csv’)
ascii.write(table,”output.csv”,format=‘csv’)
Does not yet automatically recognize .csv extension
Add tests for CSV in io.ascii
Add CSV test file
Up Time's __array_priority__ to above Quantity's
Merge pull request #1940 from mhvk/time-array-priority

Up Time's __array_priority__ to above Quantity's
Add CSV option to documentation tables