a bit of cleanup
support for Minuit callbacks into python functions
Make C++ CPP macros available to python; since this is potentially as
slow as it is useless (but cute, and was available in CINT), it has to
be enabled using "PyConfig.ExposeCppMacros = True" and are only looked
up through the ROOT namespace, not on "from ROOT import *".
Note: NULL is made a special case, as it is the most useful macro.