Merge pull request #2965 from mdboom/wcs-bounds-check

Correctly detect and handle invalid input world coordinates.
ModelMeta now creates a nicer __init__ definition for models that have no parameters.
Add missing support for keyword arguments to Pix2Sky_AZP
Reorder some of the API docs a bit.
Merge pull request #3052 from embray/table/issue-3052

Incorrect dtype format used for string columns when initializing Table from rows on Python 3
Just a minor detail--I noticed that the theta parameter has a default of 0.0 in the __init__, but this default is not given to the Parameter descriptor itself.
Updated docs to reflect changes in this PR; particularly that it is no longer generally useful to manually define an __init__ and __call__ (though an example of where it is useful to define a custom __init__ is given) and the roles of the input/output class attributes are discussed.
Enable InheritDocstrings on models.  Filled out several more docstrings that could use more details, and fixed __module__ and __qualname__ on generated __init__ and __call__ methods on models.
Fix spelling [skip-ci]
Removed references to coordinates.CartesianPoints; removed unnecessary whitespace
Initial step in removing ndarray from Table
Continued migration, down 117 test fails
Fix sort and argsort
WIP fixing __setitem__
Add basic functionality for table-level setitem
Remove separate Row-based setter
Basic row setting working
Fix masking, allow for list column input by reference
Final updates, passes table tests
Add copy kwarg to BaseColumn