* lisp/progmodes/ruby-mode.el (ruby-align-to-stmt-keywords): New

* lisp/progmodes/ruby-mode.el (ruby-align-to-stmt-keywords): New
option.
(ruby-smie--indent-to-stmt-p): Use it.
(ruby-smie-rules): Revert the logic in the handling of `when'.
Expand the `begin' clause to handle `ruby-align-to-stmt-keywords'.
(ruby-deep-arglist, ruby-deep-indent-paren)
(ruby-deep-indent-paren-style): Update docstrings to note that the
vars don't have any effect with SMIE.

* test/automated/ruby-mode-tests.el: Add tests for
`ruby-align-to-stmt-keywords'.

* test/indent/ruby.rb: Update examples to reflect the lack of change in
default indentation of `begin' blocks.