Pre-filtering of input variables

[pschichtel]

Current problem

Right now songs, that are suffixes like "(feat. Artist XY)" tend to not get found in lyrics databases, because lyrics are usually available through the base name only.

Suggested solution

Use the filtering framework to prefilter the input variables before they're handed to the provider to strip these suffixes or possible other problems away. These filter rules would configured in a separate plugin config and the use should be able to enable and disable pre-filtering via settings GUI.