Add support for phrase synonyms #7
Description
Right now, the # operator (dictset) will return synonyms (similar phrases) for a given word (e.g. #fail -> "break down"). But it is not possible to search for synonyms of phrases (e.g. synonyms of "break down" -> "fail").
Add support for phrase synonyms with the syntax #"phrase" (e.g. #"break down").
The phrase should only contain words. Regex words, wildcards, and operators are not allowed. This restriction makes it easier to implement but may be lifted in the future.