Log Message:
math/kalker: update to 2.2.0

 - Fix regression with the way numbers were printed in the desktop program
 - Parse input numbers as big floats instead of as 64-bit numbers (desktop version)
 - Use ≈ more consistently, eg. when a number is rounded a bit before being \ 
printed, but not for fractions
 - Allow equations where the variable to be solved is a function argument
 - Minor improvements