Adds a row for LDraw Units (LDU) to the Dimensions panel. I find this information useful for two reasons:
1. LDraw parts are defined in LDU, naturally.
2. L3P and LDView both accept a -cg option ("camera globe" position) which may include a radius. The radius defines the distance from the camera to the "look at" origin in LDU. Specifying an explicit radius sufficient to fit the whole model helps keep renderings of different steps at a constant scale.
A string like the following should be added to the "Dimensions panel strings" section of the Localizable.strings file:
"LDU" = "LDraw Units";