reduce noise from FitPrintService

Much space in our test logs is taken by fit progress reports like

517: 
517: FitPrintService::update -> Info. NCall:6 Chi2:3.11538944e-02
517: Wall time since last call:0.00
517: height  4.500000e+00 free  4.495500e+00
517: radius  5.500000e+00 free  5.500000e+00
517: 

If this needed at all, then a tabular form would be preferable.

Also consider:

• make code more similar to ProgressHandler
• add variable to print only at each n-th iteration
• document how to switch off, or change the output