drop Python 2.6 support; remove old hacks which are no longer needed

.travis.yml

@@ -2,7 +2,6 @@ language: python
 python: 3.5
 sudo: false
 env:
-- TOXENV=py26
 - TOXENV=py27
 - TOXENV=py33
 - TOXENV=py34

setup.py

@@ -26,6 +26,7 @@
 if sys.platform == 'win32':
     includes.extend(['crfsuite/win32', 'include'])
 
+
 class build_ext_check_gcc(build_ext):
     def build_extensions(self):
         c = self.compiler
@@ -34,12 +35,14 @@ def build_extensions(self):
                 e.extra_compile_args=['-std=c99']
         build_ext.build_extensions(self)
 
+
 ext_modules = [Extension('pycrfsuite._pycrfsuite',
     include_dirs=includes,
     language='c++',
     sources=sources
 )]
 
+
 setup(
     name='python-crfsuite',
     version="0.8.4",
@@ -56,7 +59,6 @@ def build_extensions(self):
         "Programming Language :: Cython",
         "Programming Language :: Python",
         "Programming Language :: Python :: 2",
-        "Programming Language :: Python :: 2.6",
         "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
         "Programming Language :: Python :: 3.3",
@@ -71,5 +73,5 @@ def build_extensions(self):
     zip_safe=False,
     packages=['pycrfsuite'],
     ext_modules=ext_modules,
-    cmdclass={'build_ext' : build_ext_check_gcc}
+    cmdclass={'build_ext': build_ext_check_gcc}
 )

tox.ini

@@ -1,22 +1,9 @@
 [tox]
-envlist = py26,py27,py33,py34
+envlist = py27,py33,py34,py35
 
 [testenv]
 changedir = {envtmpdir}
 deps =
     pytest
 commands =
-    ; a workaround for tox bug: https://bitbucket.org/hpk42/tox/issue/176/tox-doesnt-install-the-package-being
-    pip install -I {toxinidir}/
-
-    ; run tests
     py.test {toxinidir}/tests --doctest-modules {posargs}
-setenv=
-    ; a workaround for OS X Mavericks bug
-    ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future
-
-[testenv:py26]
-deps =
-    pytest
-    argparse
-