Basic support for expanding macros bound by `macrolet'
Fix header dates
Require `cl-macs` at runtime
Make inner macrolet definitions correctly shadow outer
Tests for macrolet/cl-macrolet support
Test for normal defmacro expansion
Test for macrostep-environment-at-point
Extend macrostep-environment while printing macrolet body forms

This correctly handles macros like the following:

(defmacro with-local-do-something (&rest forms)
  (declare (indent 0))
  `(cl-macrolet ((do-something (arg) ...))
     ,@forms))

When the following form is expanded, `(do-something ...)` should be correctly
highlighted as a macro form:

(with-local-do-something
  (do-something (here)))

See `with-js` in `js.el.gz` for a real example.
Merge branch 'expand-macrolet'

Closes #7.