implements a simple sort

Column 3 will be sorted by background color.

++ Colum 0--
Colum 1 Colum 2
Colum 3 sorted
by background color
571bad value
8867
3077
571
8867red cell
Schulze077
A71
8867
30
571
886U
571
886
30
77
Albert71absolute chaos
886Ä
b077
571
8867
!0