Allow the use of non-local ReadMe files in the CDS reader
Documentation of the CDS reader class updated
General documentation updated with an example of the load of CDS tables using URLs
sip_pix2foc should subtract crpix and the end, and sip_foc2pix should do
the inverse.
Workaround for #1953.  The BinTableHDU constructor handles data that is not already in FITS native format poorly.  FITS_rec.from_columns, on the other hand, does.  So go through that first.
io.ascii.ui: typo in Error mesage?

I think this is just a typo. If not, then I don't understand what it means.
__repr__ method in Table now also returns the units

updated doctests (for __repr__ table)

updated doctests (for __repr__ table), corrected

modifying table_repr_method

show units only when atleast one column is not None. + doctests updated.

show units only when atleast one column not None. + doctests updated.

removed quotes from 'None'.

some code standardization

added test for repr method, updated changes.rst

added doctest for repr method, updated chages.rst
Added support for inputting units
Added test for units and corresponding data file
Removed unnecessary statement
Added support for inputting column description as well
Included test file in setup_package
Changed SExtractor test to include a description check
Slight improvements to model string formatting

This deduplicates a lot of `__repr__` and `__str__` code for Model
and its subclasses, so there is more consistency between different
Model classes in what their `__repr__` and `__str__` output.
Also made some slight improvements to the previous output formats.
I still don't claim this to be perfect, but it's a step in a better
direction.  In particular I think displaying the different parameter
sets as a table is nice.

These changes are a prerequisite to another, potentially more
interesting change.
trying to allow way to pass in non-local packages
fix autmodapi to properly do options for automodsumm
Fix automodapi to also get _mod_info correctly when valid-package-names is in use
Fix for corner case encountered while debugging
Documentation cleanup and clearer variable name
change from valid-package-names to allowed-package-names and document