Add string transform game mode

[pgrudzinski]

There could be string transformation mode that would display set of strings in two columns as it is now, but instead of asking player to match left strings and don't match right strings on right, it would ask them to transform right strings into left strings.

Regex input could be kept as is and use '/' to separate input from output or give two input fields to enter input and output regex.

Challenges could be randomly generated by generating random strings and randomly mangling them to create "transform to" column.

Transform tasks could constitute separate mode, or could be mixed with normal tasks.

[phikal]

I'll think about it. Definitely sounds interesting.