Extend settings to be switchable between cross-stitching and knitting

[starturtle]

Either introduce a tab structure with one tab per measurement set or a combination of drop-down mode selection that updates the size panel.

The result size settings should be interesting for all types of needlework, therefore only the other measurements should be variable.
Simple cross-stitching assumes square stitches with configurable mesh size. The stixel separators can stay in place, as the resulting stitch squares are still rectangular.