Split CSV lines in at most 2 places

[Gobbel2000]

Previously, if a transition label contained a comma, the CSV loader would truncate the label there.
This causes the following lines to be considered as transitions with the same label of "s4(d1":

66,98,"s4(d1,first)"
1636,1674,"s4(d1,last)"

The above transitions are found in the cwi_1_2.csv benchmark file. This issue caused only 9 enabledness-classes to be detected instead of 11.

This fix changes the behavior so that a line is split in at most 3 parts, everything after the second comma goes into the label.

[benkeks]

Great, thanks!