Implement `delete` instance method in enumerable mixins.

This is a "self-destruct" method to accompany
`removeAt(...)`. Elements of arrays and objects can now delete
themselves.
track built files
fix delete test for hashes; fix removeAt for hashes

Previously, the hash test was indented one too many times, and didn't
run. It failed, and the changed to enumerable.coffee make it run.
throw an error when removeAt is called on primitive type

This replicates what would have happened before if `removeAt` were
called on a non-array wrapper.
add built files
Merge pull request #3 from drfloob/feature-enum-delete

Implement `delete` instance method in enumerable mixins.