Change table Row __eq__/__ne__ methods to raise for masked Table
Change table Row __eq__/__ne__ methods to raise for masked Table

This is in response to a bug in numpy.ma which doesn't allow
comparing structured masked array rows.  Below is the issue report
sent to numpy-discussion:

When comparing rows of a structured masked array I'm getting an
exception.  A similar operation on an structured ndarray gives the
expected True/False result.  Note that this exception only occurs if
one or more of the mask values are True, since otherwise both row
objects are np.void and the ndarray behavior is obtained.  (See PR
notwithstanding).

>>> from numpy import ma
>>> marr = ma.array([(1,2), (3,4)], dtype=[('x', int), ('y', int)])
>>> marr.mask[0][0] = True
>>> marr.mask[1][0] = True
>>> marr[0] == marr[1]
Traceback (most recent call last):
  File "<ipython-input-5-fecaee6f2991>", line 1, in <module>
    marr[0] == marr[1]
  File "/data/cosmos2/ska/arch/x86_64-linux_CentOS-5/lib/python2.7/site-packages/numpy/ma/core.py",
line 3573, in __eq__
    check = ndarray.__eq__(self.filled(0), odata).view(type(self))
TypeError: descriptor '__eq__' requires a 'numpy.ndarray' object but
received a 'numpy.void'

>>> arr = np.array([(1,2), (3,4)], dtype=[('x', int), ('y', int)])
>>> arr[0] == arr[1]
False

>>> np.__version__
'1.6.2'

funbaker/astropy,pllim/astropy,larrybradley/astropy,larrybradley/astropy,kelle/astropy,StuartLittlefair/astropy,mhvk/astropy,lpsinger/astropy,larrybradley/astropy,StuartLittlefair/astropy,dhomeier/astropy,joergdietrich/astropy,DougBurke/astropy,tbabej/astropy,MSeifert04/astropy,mhvk/astropy,AustereCuriosity/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,astropy/astropy,lpsinger/astropy,astropy/astropy,dhomeier/astropy,pllim/astropy,aleksandr-bakanov/astropy,DougBurke/astropy,bsipocz/astropy,AustereCuriosity/astropy,kelle/astropy,mhvk/astropy,tbabej/astropy,stargaser/astropy,pllim/astropy,MSeifert04/astropy,saimn/astropy,DougBurke/astropy,joergdietrich/astropy,astropy/astropy,kelle/astropy,AustereCuriosity/astropy,stargaser/astropy,joergdietrich/astropy,AustereCuriosity/astropy,mhvk/astropy,joergdietrich/astropy,saimn/astropy,lpsinger/astropy,larrybradley/astropy,saimn/astropy,larrybradley/astropy,DougBurke/astropy,pllim/astropy,mhvk/astropy,tbabej/astropy,astropy/astropy,pllim/astropy,MSeifert04/astropy,StuartLittlefair/astropy,astropy/astropy,stargaser/astropy,funbaker/astropy,lpsinger/astropy,tbabej/astropy,bsipocz/astropy,funbaker/astropy,dhomeier/astropy,kelle/astropy,bsipocz/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,joergdietrich/astropy,saimn/astropy,bsipocz/astropy,dhomeier/astropy,kelle/astropy,StuartLittlefair/astropy,funbaker/astropy,AustereCuriosity/astropy,tbabej/astropy,MSeifert04/astropy,stargaser/astropy,saimn/astropy