Search: Limit amount of search results

[JurgenR]

The amount of search results that can be returned by a query should be limited. Users can currently run queries that return a large set of results, for example a query for simply the word "mp3" can return pretty much a user's entire library. Such queries have very little value and returning everything that matches makes no sense here.

The current search algorithm keeps a set of words for optimization, but then performs a slower regex anyway to ensure the file actually matches the query.

This limit should be configurable but a default of 100 seems reasonable.