First steps on auto mode

Apparently the unfoldings are not added for things not used enough (?).
If I comment out the signature in Integers, there are no unfoldings
at all generated (!). So we need to carry around a little map of
bindings. However, imports from other modules have seemed to work properly
before, and for example the HipSpec.Prelude imports work correctly.
Also add the missing files
Add a pass that fixes the unfoldings
Add auto mode that works
Refactor
Support the --only flag

Todo: --extra-funs flag
Fix a bug in MainLoop
Add --extra and other flags to --auto signatures
Update examples