`py--emacs-version-greater-23', internal function

use it
`py-execute-line', menu added
use -bol, beginning-of-line, ending rather than -lc
Move stops at beginning-of-line forms, menu added
beginning-of-line copy forms, menu added
More useful doc-strings WRT beginning-of-line forms
Menu "Mark" beginning-of-line forms separate entries
Menu: move "TAB related" into "Indent"
backward compatibility

provide alias for `py-goto-beyond-block', `py-goto-beyond-final-line'
Some third party stuff relying on v5 serie might use this
module completion, lp:1284141

fixed