Comparator is now case insensitive

[PhilLab]

Output with case sensitivity (old behavior):

Sorted: [1-2, 1-02, 1-20, 10-20, POLITELY SCREAMING, fred, jane, pic01, pic02, pic2, pic02a, pic3, pic4, pic 4 else, pic 5, pic 5, pic05, pic 5 something, pic 6, pic 7, pic100, pic100a, pic120, pic121, pic02000, politely, tom, x2-g8, x2-y7, x2-y08, x8-y8]

output after this change:

Sorted: [1-2, 1-02, 1-20, 10-20, fred, jane, pic01, pic2, pic02, pic02a, pic3, pic4, pic 4 else, pic 5, pic05, pic 5, pic 5 something, pic 6, pic 7, pic100, pic100a, pic120, pic121, pic02000, politely, POLITELY SCREAMING, tom, x2-g8, x2-y7, x2-y08, x8-y8]

The usecase for natural ordering is most often to produce an ordering which a human "expects". Case insensitivity might also be expected so I added it here. One could maybe discuss whether the case should be used again when breaking ties (which this PR does not).