Fix equality for array coordinates

Closes #1832
Added test for #1832 failure mode
update changelog
Documented classes in ascii.core
Adjusted for numpydoc convention
Merge pull request #2142 from amras1/document-ascii-classes

Documented classes in io.ascii.core
Fix backtick error pointed out by @embray

[ci skip]
Merge pull request #1832 from eteq/fix-1832

Coordinates equality comparison fails for array values
Add __call__ to Sphinx API docs (fixes #1817)