Improve module search

[frauzufall]

This PR adds the following search features to ModuleSearcher:

• searching the menu
• searching for parts of the search string divided by space individually

It also adds a bunch of tests for the ModuleSearcher.

Ideally we would use a fuzzy logic algorithm. I would like to integrate fuzzywuzzy, but it's GPLv3 licensed which might be an issue?

[ctrueden]

Thanks a lot, @frauzufall!