Remove brainfart, should've been "left" instead of "0" #14

position() is relative to begin with anyway
Add new options for group seaprators #14
Calculate col position consistently #2
Consider group separators when snapping to grid #14
Remove duplicated logic #14
Improve logic from calculating col positions #14
Optimize method for getting closest column #14
Merge branch '14-separators-2' into grid-columns