* Fix typo in type name (duk_int -> duk_int_t)
* Fix value stack index usage for safe call, was using positive indices
* Add exitcode to test.c so that 'make test' errors out
* Add exitcode to other extras too where applicable
This loader has the following features:
* Application-provided callbacks for module resolution and loading
* Module caching based on resolved module ID
* Tolerates circular `require()` chains
* Supports `module.exports`, `module.loaded`, and `module.require`
* Supports `require.cache`
* Supports `__filename` (but not `__dirname`)