reorg
add dependencies

- direct dependency to omicron
- devDependency to coffee, for mocha in test scripts
drop util package
add "static abstract" `promise` function
drop util package

- still need to add standalone isError (should be added to omicron)
rename `assimilate` to `transform`; reformat

- “assimilate” would be ambiguous to common usage
clarify docs
expand `join` and its satellites

- add subsetting, polarity
- fill documentation
reorg