Clean up a few building function names
Split apart a too-large function
Remove unused functions
Use an array for BuildingPart name instead of pointer to array

This seems to be expected elsewhere, like outliner code. IMO placing
such an artifial limit isn't nice, but much better than crashing on
outliner rename.
Use BLI_strncpy_utf8 instead of BLI_strncpy

Seems like the right thing to do since this field is user-editable and
could contain non-ASCII text.
Add RNA for BuildingPart.name
Clean up building UI, add edit-part name/type label