Improve argument checking & reduce strings to translate

[jepler]

This needs to be tested, it's only compile-tested.

[dhalbert]

One suggestion, otherwise these look ok to me. Thanks for doing this. I didn't concentrate on these when I squeezed the other messages because these are used (mostly?) on boards with plenty of flash.

[jepler]

I ended up rebasing it, was getting weird conflicts but they're gone now.

[dhalbert]

OK, looks good, thanks for this cleanup and space saving!