New filter: highlight only

[BoySka]

I saw the #11 issues and, while that might clearly be cool, I have a proposal that might be less difficult and more flexible.

The idea is to add a new "filter" that actually doesn't filter out any lines. Instead, it highlights something. Say, for example, you have this chain:

-DEBUG
-INFO
%ERROR

this will leave you with both warning and errors, but the "error" keyword will be highlighted, for greater readability. The word ERROR might then be printed in reverse colors, or some other simple effect.