Change shebangs to python from python2

Also remove a few other miscellaneous references to python2

src/odf/element.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2007-2010 Søren Roug, European Environment Agency
 #

src/odf/elementtypes.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2008 Søren Roug, European Environment Agency
 #

src/odf/load.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2007-2008 Søren Roug, European Environment Agency
 #

src/odf/manifest.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2006-2007 Søren Roug, European Environment Agency
 #

src/odf/odf2xhtml.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2006-2010 Søren Roug, European Environment Agency
 #

src/odf/odfmanifest.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2006-2007 Søren Roug, European Environment Agency
 #

src/odf/thumbnail.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # This contains a 128x128 px thumbnail in PNG format
 # Taken from https://cgit.freedesktop.org/libreoffice/core/tree/sysui/desktop/icons/hicolor/128x128/apps/main.png

src/odf/userfield.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (C) 2006-2009 Søren Roug, European Environment Agency
 #