python.el: New non-global state dependent indentation engine.
Fixes: debbugs:18319 Fixes: debbugs:19595
* lisp/progmodes/python.el (python-syntax-comment-or-string-p): Accept
PPSS as argument.
(python-syntax-closing-paren-p): New function.
(python-indent-current-level)
(python-indent-levels): Mark obsolete.
(python-indent-context): Return more context cases.
(python-indent--calculate-indentation)
(python-indent--calculate-levels): New functions.
(python-indent-calculate-levels): Use them.
(python-indent-calculate-indentation, python-indent-line):
(python-indent-line-function): Rewritten to use new API.
(python-indent-dedent-line): Simplify logic.
(python-indent-dedent-line-backspace): Use `unless`.
(python-indent-toggle-levels): Delete function.