Error Explanations

[ZeroIntensity]

Proposal:

See #170 for details. This will be an extraordinarily long issue.

Example API:

$ python3 someapp.py

view.exceptions.SomeException: [Code VE1000] this is the error message
`view explain VE1000` for more information

This issue will likely include a explain.py containing a very long set of error explanations. Alternatively, perhaps it could just be written in markdown, and then vendored into view.py at build time.