Abbreviations aren't locale specific

[jacobras]

Abbreviations (introduced in #36) and file sizes don't have localisation support.

Example 1

1_000_000 with 2 decimals becomes "1.00M". That's fine in English, but for Dutch it should become "1,00M" (possibly with a space? https://nl.wikipedia.org/wiki/SI-stelsel#Consequent_gebruik)

Example 2

File size "21.43 kB" should be "21,43 kB" in Dutch.

Example 3

File size "21.43 kB" should be "21,43 kO" in French.