Add Whoosh as an alternate search backend

[ghtyrant]

I've added Whoosh (https://bitbucket.org/mchaput/whoosh/wiki/Home) as a search backend to the search module.

Few notes:

• I'm not a Whoosh expert. There might be ways to improve search results, someone with more Whoosh experience should check my code
• I'm not quite happy with the large amount of in-function imports (especially in WhooshSearch.init)
• I use LanguageAnalyzer per default with a fall-back to SimpleAnalyzer in case the desired language is not supported by Whoosh. Should Realms display a warning if that's the case? If so, what's the preferred way to do so?

[scragg0x]

This is great! I will try it out when I get a chance. I might make this the default, rather than the simple search since it doesn't require any extra running services. The in function imports are fine afaik. It will decrease overhead for people that choose to use a different search type.

I think how you handled the language analyzer is fine. I may add an application wide language config option and whoosh and other things can reference that.

[zeigerpuppy]

whoosh search doesn't seem to be working for me, it returns empty results. The index is created, so I know its not a permission issue. Is there any way to debug this?