[sayomaki]

This PR adds support the python autograder, using the py2js backend in py-slang. Python evaluation results are captured from the print output, so any testcases must print the result.

Notable changes:

• New script to build the runtime of py2js, with compiled version committed under vendor/
• Split up the python autograder and legacy javascript autograder into separate files
• Updated tests to work with python autograder and added some new tests for grader dispatch and python evaluation

The python autograder is chosen and used by default, if it is needed to use the legacy javascript grader, the language field from the autograder payload must be specified to be javasacript.

Currently, runes and other modules are not working in the python autograder, support will hopefully be added in a future PR.

[sayomaki]

I'll just go ahead and merge this, it is pretty important to get the autograder working.