Remove references to the access() mechanism from the emulator.

This allowed code to access things defined in other libraries
when using the emulator (I think).
[dfmc-testing] Switch typist-inference tests to testworks.
[crt] Break NLX code into separate file.
[dfmc-modeling] Remove method environment(<&method>).

This method wasn't used and returned an empty vector rather than
a valid environment object.
Merge pull request #780 from waywardmonkeys/c-primitives-nlx

[crt] Break NLX code into separate file.
Merge pull request #779 from waywardmonkeys/remove-access-emulator-relic

Remove references to the access() mechanism from the emulator.
[dfmc-modeling] Tighten types on environment generic & methods.
Update testworks submodule.
Merge pull request #782 from cgay/submodules

Update testworks submodule.
[dfmc-flow-graph] Correct error in <values> code in debug-back-end.

This shouldn't pass the fixed values here.
[dfmc-flow-graph] Fix typo.
[dfmc-typist] Correctly check for empty fixed values.
Merge pull request #783 from waywardmonkeys/minor-cleanups

Minor cleanups
[variable-search] Correctly implement on OS X.

On Mac OS X, we just want to pass RTLD_DEFAULT to dlsym() rather
than a handle from dlopen() (which doesn't work).
[variable-search] Reorganize to share more code.
[variable-search] Add tests.
Merge pull request #784 from waywardmonkeys/variable-search-improvements

Variable search improvements
Remove unmaintained PowerPC OS X materials.
[build] Allow installing on top of an existing install.

Fixes issue #753.
Merge pull request #786 from waywardmonkeys/allow-install-on-top

[build] Allow installing on top of an existing install.