Wrong number of arguments, lp:1207470, fixed

Keep backward compatibility
`delete-trailing-whitespace' takes args only since 2011-02-11
See ChangeLog.15
Non indenting colon, lp:1207405

Menu in Python/Customize/Switches/Indent toggles `py-electric-colon-active-p'
dedicated forms fixed

Internals normalized, "buffer"-, "file"- and "region"- forms use `py-execute-prepare'
Non-indenting-colon, lp:1207405, fixed