Update README

Consolidate license text

Update README.md

Rename defs to deft. Add doc.

Cosmetics.

Make Fn a type also.

Update readme.

Add custom type to test; add keyword type.

Check arrity;add helper functions;more tests.

Update README.md

Update readme with custom type example.

Update gitignore.

Update readme with an example; add some tests; add not valid signature exception message.

Initial commit.