[docs] [issue15629] Add to regrtest the ability to run Lib and Doc doctests

Brett Cannon added the comment: I should mention that http://bugs.python.org/issue10967 exists as a meta issue about trying to gut regrtest in favour of using other things in unittest (and doctest in this case) when possible. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue15629> _______________________________________