rubi integrate

[Edward Montague]

 After wrestling with version incompatibilities and incomplete
code, I have produced test code and an edited version of
rubi.py  .
 For rubi.py I found it necessary to replace exp with rubi_exp,
in a few locations; you may want to check this, files are attached. Perhaps
this isn't an issue with a more recent version of sympy.

I'm using Ubuntu 19.10, python 3.7.6, gcc  7.3.0, pip3 version
20.0.2.
  Sympy 1.4, matchpy 0.5.1, numpy 1.8.1, scipy 1.3.3 .