add support for operator symbol anchors to inferior-haskell-find-haddock

For operator anchors encode operator names into sequence of `-<ascii-code>-` strings for each operator character, as haddock does. As operators may be qualified, which is not a rare case for `Data.Map.!` and other container-oriented operators, the function for qualification removal along with tests is introduced. And supply anchor for local paths.

Also, I've added regexps for vanilla and qualified operator names, since the only other place where remotely similar regexp can be found is syntax definitions in haskell-mode.el, but `-` and `\` characters are treated differently there. If this addition seems redundant or if better solution exists, please tell me.