improve or remove parsing of Tkinter.__version__ required for newer python versions

[vbkhp@…]

due to the cpython hg transition the version attribute of tkinter has been removed in python 3 and in the python 2.7 rc1 it does not contain a number anymore.

This breaks the py27-matplotlib build which parses version and expects a number:

see ​https://github.com/matplotlib/matplotlib/commit/04b4e5091978 on how to fix it.

OPTIONAL BACKEND DEPENDENCIES

libpng: 1.2.44

Traceback (most recent call last):

File "./setup.py", line 162, in <module>

if check_for_tk() or (optionsbuild_tkagg? is True):

File "/build/buildd/matplotlib-1.0.1/setupext.py", line 832, in check_for_tk

(Tkinter.version.split()[-2], Tkinter.TkVersion, Tkinter.TclVersion))

IndexError: list index out of range