<rdar://problem/12028723>

Adding useful formatting options to the expression (expr) command.
As a side effect of this change, the -d option now supports the same three-values enumeration that frame variables uses (run, don't run, none) instead of a boolean like it did previously

These options do not apply to print, p or po because these are aliased to not take any options.
In order to use them, use expression or expr.