* lisp/progmodes/ruby-mode.el (ruby-indent-beg-re): Add pieces from

* lisp/progmodes/ruby-mode.el (ruby-indent-beg-re): Add pieces from
ruby-beginning-of-indent, simplify, allow all keywords to have
indentation before them.
(ruby-beginning-of-indent): Adjust for above.  Search until the
found point is not inside a string or comment.
(ruby-font-lock-keywords): Allow symbols to start with "@"
character, give them higher priority than variables.
(ruby-syntax-propertize-function)
(ruby-font-lock-syntactic-keywords): Remove the "not comments"
matchers.  Expression expansions are not comments when inside a
string, and there comment syntax status is irrelevant.
(ruby-match-expression-expansion): New function.  Check that
expression expansion is inside a string, and it's not escaped.
(ruby-font-lock-keywords): Use it.

* test/automated/ruby-mode-tests.el: New tests (Bug#11613).