Use candidates-file instead of grep process as suggested by Thierry.
Remove helm-dictionary-ignore-case defcustom.

Not needed anymore because now we're not using grep but Emacs' search
facilities: Searches are case-insensitive unless a capital letter is in the
search expression.
Removed unnecesary save-excursion.

Only needed with asynchronous sources.
Removed the transformation of helm-pattern in the transformer.

It's not needed anymore because there are only candidates iff helm-pattern was
a valid regexp.
Improved helm-dictionary-transformer.

* Removed the redundant loop over the candidates.
* Added a sanity check for the candidates to avoid a complete failure when an
  entry is malformed.
Made the parser for dictionary entries more robust.

This addresses the cases that Thierry brought up in issue #13.
Simplifies the code in helm-dictionary-transformer.

Following Thierry's suggestion.
Merge branch 'master' into candidates-file
Updated documentation: grep isn't backend anymore.
helm-dictionary.el: Updated documentation.