Add bare bones `localExpand`

This is a simple implementation of local expansion. It currently does
not support stop lists, but fully expands the syntax given to it.
refactoring, moving TermTree to its own file
some renaming
adding export entry and related tests
expander is now using the export entries
getting more import forms working
fixing up toTerm for import entries
error messages, cleaning gruntfile
starting the default import/export work
modularizing resolve and string map
adding immutable js
breaking out the environment to its own object
switching to environment object
more refactoring of the env
preparing for store
Merge branch 'pr/310' into localExpand

Conflicts:
	src/expander.js
destruct needs to strip compiletime
adding var transforms to the environment #310
adding test for localExpand and local macros #310