General refactor

[hlissner]

This brings a few large scale changes:

• A Domain class, which marshals input and self-validates
• The removal of the process and check modules; most of which has been moved into Domain, as that is the only place they are used
• A new config module with helpers for succinctly type-checking the user config
• Absolute paths for local imports (no more relative shenanigans, i.e. ../../../../)
• Slimmed down on nesting and code redundancies
• Laid out some JSdoc blocks for better documentation (and hinting for smarter editors)
• And updated the unit tests to reflect these changes.