Break out the system and known word checkers into separate packages?

[dmoonfire]

I'm not sure if this is feasible, but would it make sense to break out the known words and system checker implement for #120 into separate packages? That way, a user could disable the system checking as opposed to have a checkbox in settings that turns it off. The same with known words.

There would be a bit more logic written in the main class to handle settings changes, but the logic is pretty well-isolated.

It would me adding two new packages to the default install.

It just occurred to me while writing up #153.

[dmoonfire]

cc: @as-cii