Generating builtin srclocs for the wrapped lets of a module, so that the imported names don't look like they've been defined locally.  Fixes #237.
Adding a new runtime error when trying to functionally extend a non-object value.  Fixes #241.
drafting equality
parse ref statements
ref modifiers in objects and data
remove cyclic, and make REF create s-mutable-fields
consolidate shared split-* code
refactor scope resolution to create fewer blocks and treat binding groups more uniformly
include more information (hidden) on exn objects (used in browser for error reporting), and catch errors at check-block boundaries
bootstrap with unwrap-exn
Adding some well-formedness checks.

* Prevents underscores in binding position inside graph.  Fixes #243
* Prevents underscores being used as vars
* Prevents underscores being used as shadowed ids
* Prevents duplicate fields in an object literal
Fix Set bugs caused by mixing constructors.
fixing the locations of underscore vars and shadows.  also filtering out underscore names in repl-support, since that happens before well-formedness gets to complain...
Subtle name-resolution bug in resolving the parameters of for-loops, and a regression test to make sure we don't make this mistake in the future.  Basically, the values being bound as the initial values to the looped function should be resolved in the environment outside the loop, while the names of the parameters are accumulated to provide the environment inside the loop.
Fixing the reporting of error locations when they occur on the right-hand-sides of cases branches.  Fixes #245
Several bugs, which together fix #246.  See the comment in the new regression test for details.
these are pretty final now
New check-test op forms: is-not, satisfies-not, is%(eq), is-not%(eq).
Also, added basic test cases for all check-test ops.
Emacs: pyret mode support for new keywords: is-not, satisfies-not
Merge branch 'master' of https://github.com/brownplt/pyret-lang