With 2.0.1, and setuptools 34.0.2, errors happen like:

File "/edx/app/edxapp/venvs/edxapp-sandbox/local/lib/python2.7/site-packages/packaging/requirements.py", line 59, in <module>
    MARKER_EXPR = originalTextFor(MARKER_EXPR())("marker")
TypeError: __call__() takes exactly 2 arguments (1 given)

(cherry picked from commit 73519b35)

Signed-off-by:  <manuel.freire@fdi.ucm.es>

..because that is where it is the most annoying/visible. Otherwise it really
has no effect on the LMS or anything else.

- Create a method called `parse_algebra`. It takes a string of math and returns with a `pyparsing.ParseResults` object representing it.
- `evaluator` takes this tree and applies the old "parse actions" to it to get the same number as it used to.
- Change calc's API: `evaluator` to use `case_sensitive` rather than `cs`
- Add most of the capability for latex rendering

Especially the var[0].isdigit() one.

-Clean up `SUFFIXES` from interspersed commented-out suffixes
-Remove unused `LOG`
-Remove unused method `raiseself` of UndefinedVariable and its usage