is completely contained within lib/dogfood, and it can be cleanly unplugged
from the rest of the code.

for now

with external server into ExternalResponse.do_external_request

for getting expected answer from external server, add error handling,
extend to use json for multiple input fields, added rows & cols to
textbox inputtype for code input.

also some changes to try to fix the codemirror problem

cleaned up some cruft prints -> logging

symmath library; add options for matrices, qubit to symmath_check

after click due to call to content_updated(); fixed this.

generated when Check is clicked)

capture the error message and traceback and show this as the problem text.

main.html now includes mathjax_include for all mathjax stuff
problem.js refreshes mathjax formulas on change
all previous *_fromjs renamed to *_dynamath, eg textline_dynamath

to use logging; added DEBUG attr to XModule class

urls, courseware.{views,module_render}, comments added to seq_module

problem.js (commented out)