Abbreviate quantity overlay on icons

If a quantity is over 1000, we remove the last 3 digits (integer divide
by 1000) and add a "K" suffix. Then the actual total is displayed in the
item's long tooltip next to its name.
Move kilo abbreviation to Util function and make "k" translatable
Remove unnecessary variable
Merge pull request #705 from dorkster/quantity_abbr

Abbreviate quantity overlay on icons