Replace the obsolete wx.PySimpleApp

Change the obsolete wx.PySimpleApp to wx.App to fix the DeprecationWarning in wxpython 2.9.
fix the docstring for scale_docs to only strip whitespace at the end (the whitespace at the beginning is needed for alignment)
Merge pull request #2317 from deanmalmgren/fix-scale_docs

fix the docstring for scale_docs
Merge pull request #2316 from vbr/patch-6

Replace the obsolete wx.PySimpleApp