Fix ValueError: could not convert string to float on Windows/MikTeX

[cgohlke]

On Windows with MikTeX 2.9, the backend_pgf backend frequently fails with

  File "X:\Python32\lib\site-packages\matplotlib\backends\backend_pgf.py", line 348, in get_width_height_descent
    w, h, o = float(width[:-2]), float(height[:-2]), float(offset[:-2])
ValueError: could not convert string to float: '2.49608p'

[pwuertz]

Oh nice, you already tracked the problem down to parsing the font metric query? Could you tell me what exactly went wrong on Windows? Do you have an example string that couldn't be parsed correctly?

I'm wondering.. \typeout{\the\wd0,\the\ht0,\the\dp0} should not cause latex to add any whitespaces :/

[cgohlke]

Turns out the end of the split line was and \r. No need to strip all strings.

[pwuertz]

Ah, I was afraid of something like that. For the sake of python3 support I had to remove the "universal_newlines" parameter in subprocess.Popen.. but I think this should be the only incident. Can you squash the commits to a single fix?

[cgohlke]

Just ignore this PR and apply the change with a better commit message.

[pwuertz]

All right, fixed in #1240
Thanks for tracking this down!