Tackle the Python dependencies versus plugins issue

[gingeleski]

It's occurred to me that while plugins are currently really modular, they typically carry overhead in the form of Python dependencies they need.

So that "modularity" is sandbagged by the fact that the overall requirements.txt file has to be updated to include those.

This is a design issue which needs to be addressed in one form or another... maybe alongside #32

[gingeleski]

Gave this some thought; think plugin interface should have each of them declare a list of dependencies.

Somehow these are all sorted out into one consolidated requirements.txt.

It's better than how things are currently, until I/"we" figure something even better than this.

[gingeleski]

Prototyping this in a separate branch

[gingeleski]

Currently missing requirements for the plugins in requirements.txt ... have to diff, isolate the ones needed, then add some field (DEPENDENCIES ?) to the plugin interface before finally adding back the specific deps as needed

[gingeleski]

Things this needs still:

• Documentation updates throughout
• Testing
  • Manual for now
  • Later will address in Add initial round of unit tests #34