Flag armor that conflicts with other armor

[XerWolf]

You can freely combine multiple pieces of armor that don’t cover the same hit location, but you can only layer armor if the inner layer is both flexible and concealable. Add the DR of both layers (pg 286)

If 2 armor pieces modify the same location and one isn't flexible and concealable then display errors for the armor pieces that aren't flexible and concealable.

[richardwilkes]

This has similar issues as your other request: #759