Wish parser should translate "leather armor" to "light armor"

[copperwater]

This would be a backwards-compatibility shim, because probably 99% of the time when someone wishes for "leather armor" in xNetHack, they want to get the base-leather piece of armor that provides 2 AC, not any random object in ARMOR_CLASS that happens to have its material set to leather.

So the token "leather armor" in a wish should:

• be parsed into LIGHT_ARMOR
• not have the "leather" mean anything