lisp/org.el: Function rewritten

* lisp/org.el(org-regexp-group-p): Rewrite.

The old version was fooled by consecutive subgroups that were not
enclosed in one single group. Since it seemed impossible to detect
regexp groups by pure regexp matching, the new version combines lisp
function `forward-sexp' with regexp-matching to detect a
regexp-group.
lisp/omm.el: Refactor org-regexps conversion

* lisp/omm.el(org-BOL,. org-EOL, org-STAR): Org variables declared
  instead of defined in omm.el
  (omm-org-stars-alternatives): Backslashes escaped.
  (omm-bol-regexp, omm-eol-regexp): Removed.
  (omm-convert-static-to-dynamic-regexp): Rewrite and simplify.

Furthermore require org.el now.
lisp/omm.el: Comment-cruft removed

* lisp/omm.el(omm-org-bol-regexp-matcher, omm-org-bol-regexp-matcher):
  Outcommented functions removed.
lisp/omm.el: Keybindings fixed

* lisp/omm.el: Keybindings wrapped in lambda expressions.

Furthermore some fixes in regexp conversions.
lisp/org.el: Funktion org-rx improved

* lisp/org.el(org-rx): Make syntax and treatment of function argument
  STARS more powerful.

Enable `org-rx' to map the many different ways Org stars are
hard-coded in Org regexps.
lisp/omm.el:

* lisp/omm.el(omm-org-regexp-matcher): Tiny regexp improvement.