going back to happier times, before no-helper-funs merged
re-applying jasmine version change
re-apply require for s-expression
explicitly instantiate all the trove modules ahead of time
Add s-exp built-in library for parsing s-expressions

- Add new string-isnumber function for testing if a string can
  be converted to a number
- Require s-expression library from npm as a dependency
- Tests and runtime function for reading s-exps
Don't allow expressions for field names in objects.

Previously, code of the following form was legal in the grammar:

  { ["he" + "llo"] : 5 }

This commit changes this, so that it is now illegal. This is the first
step towards changing the AST to not use the Expr type in Member, and
instead use something like String or Name.

Note that strings are now allowed in the field name position. For
example:

  { "5" : 5 }

This may not stay, since the only way to access such fields is by
converting them into a string dictionary (see to-dict() in string-dict).
re-applying member name change
Made test for Option more correct (passed either way)
Raise an exception on already desugared s-let and s-var in desugar
Add some more annotations to resolve-scope
rebootstrap with re-applied changes
Merge branch 'master' of github.com:brownplt/pyret-lang