Exceptions

[dbhart]

Summary

Provides updated EpanetException class and subclasses that allow for cleaner error reporting during IO.

[coveralls]

coverage: 86.717% (-0.06%) from 86.774%
when pulling 806b04e on dbhart:exceptions
into f07682b on USEPA:main.

[dbhart]

@kbonney I see you also have a PR in to do some work on Exceptions. I know that the request with MSX was that we somehow use the same error codes as EPANET does in wntr.epanet.msx.io, and I started setting that up for wntr.epanet.io also, but I think we did this in parallel and should try to merge our approaches. :-)

[kbonney]

Thanks for bringing this to my attention @dbhart. I think we can stick with what you've proposed here and I can adjust the contents of #374 to fit within that framework.

[dbhart]

Trim down (remove Enum) and create some tests

[dbhart]

@kaklise added tests for exceptions

[dbhart]

Added documentation file, links to it, tests, and the files are now all up to date.

[dbhart]

Todo to finish this PR:

• Get rid of errors.rst file
• Finish testing
  • Break an INP file (disconnected node)
  • Write test to call toolkit and get an error
• Remove *_control from toolkit