Preparing for next iteration.
A first go at adding arbitrary function dispatch.
Revert "A first go at adding arbitrary function dispatch."

This reverts commit ffab18e4446cfa8bafdf3d91c5c4ff1c24124c9c.
Docstrings for all function transformations.
Support for eager prehooks.
Tests for prehook using supervise.
Tests for mutation on eager prehooks, plus docstrings for banged fns.
Update README for eager prehooks.
Bump version to 0.4.2.
Merge branch 'develop'