Disclaim compatibility with Python 2.6.

Author: pavoljuhas

README.rst

@@ -20,7 +20,7 @@ is available in the doc/Farrow-jpcm-2007.pdf paper.
 REQUIREMENTS
 ------------------------------------------------------------------------
 
-PDFgui requires Python 2.6 or 2.7 and several third-party libraries
+PDFgui requires Python 2.7 and several third-party libraries
 that are used by PDFgui and its components.
 
 * setuptools   - tools for installing Python packages

setup.py

@@ -125,7 +125,6 @@ def dirglob(d, *patterns):
             'Operating System :: MacOS',
             'Operating System :: Microsoft :: Windows',
             'Operating System :: POSIX',
-            'Programming Language :: Python :: 2.6',
             'Programming Language :: Python :: 2.7',
             'Topic :: Scientific/Engineering :: Chemistry',
             'Topic :: Scientific/Engineering :: Physics',