[petsc-dev] Python 3 support in configure

[Jed Brown]

Configure now supports Python 3.4+ in addition to the prior Python 2.6+
support.  If you are working on configure, please test with Python 3.
For example, observe that print is a function and map() returns a map
object so you'll need to use

  [f(x) for x in xs]

or

  list(map(f, xs))

if you require a list.  Please let us know of any issues you may
encounter.