Update vertex_instructions_line.pxi
fix clipboard_pygame.py to encode only for py2
Style Guide Fixes:Pep8
Update clipboard_pygame.py
Merge pull request #2760 from kivy/styleguide_fixes

Style Guide/Pep8 fixes
doc: Corrected and improved size_hint doc
Merge pull request #2763 from inclement/size_hint_doc

doc: corrected and improved size_hint doc
doc: Fixed defaultvalue name in docstrings