Started working on a "Free Reverse Test"
Fixed a bug where a small white dot appears after clear
First working version of the "Free Reverse Test"

In this first version you have to decide yourself if your answer is
correct.
Optimised size of reference image
Made it more clear which part of the UI is active
Updated Readme

Included a short description of the "Free Reverse Test" to README.md
Made UI a bit darker

This should be better for the screen of the Jolla
Increased width of drawn line
Made UI respect Theme colors
Redesigned UI of "Free Reverse Test"
Added some description
Merge branch 'free-reverse-test'