I've tried to set it to true by default, but it is still buggy.

 - Handle jedi-vim call signatures when looking for colon and function
   def in previous line.
   This adds `jedi\S` to s:skip_special_chars and improves the algorithm to
   find the colon in the previous line in `s:indent_like_previous_line`.
 - Add `s:match_expr_on_line` and use it for `nothing_after_opening_paren`.
 - Handle comments after opening paren (#32).

NOTE: This handles older Vim versions, where `synconcealed` behaves different
(returns an empty list for non-concealed) and `getcurpos` is not
available (Vim 7.3.429 (used on Travis)).

Fixes: #32