Split extraction of body parts singular and plural names for better translation

[cainiaowu]

Currently they are treated as one entry in generated .pot file.

#: lang/json/bodypart_from_json.py src/armor_layers.cpp
msgid "R. Foot"
msgid_plural "Feet"

I dont know how to make Transifex accept two different translation, so we might as well split them into two entries.

[Wuzzy2]

I agree. Using 2 separate strings makes more sense. The Gettext plural form feature is designed for strings which contain an arbitrary number. In this case, however, it's not needed.

If you're unsure, you can add a translator comment or context to the new strings.