Bare minimum refactor to pass the metrics
Pass most compliance tests

No import or multiline string support yet
Beta normalization complete
Implement "shift" function for variable indices
All beta normalization except for functions
Remove swap files
First pass refactor
Implement many builtins and do Optional section
Start to implement normalization rules
Start creating comprehensive normalization tests

Take all the rules from semantics.md and turn each into a trivial test
case for that rule.  This allows TDD creation of the implementation of
the rules.
rubocop fix for Gemfile
Add backports for rubocop
Add initial COPYING
Decoding Dhall from binary works