Colors of several output panes not always readable on dark themes

If you're using colored output for some reason, it may be hard or even impossible to read the text on several output panes.

Examples: create e.g. boost tests and run it with following arguments

-r detailed -l all -x 

inside QC without using an external terminal.

Please, investigate how the fine tuning of the OutputFormatter  (src/libs/utils) or the AnsiEscapeCodeHandler could be tweaked to make colors readable on any theme.

Note: I recently moved some function into the Utils library (isReadableOn()) that might be helpful..