Make brevity of constant domains configurable per-constant

- The reason for this is mostly that we would like to have some
  constants (those represnting location expression operations in
  particular) brief, but would still like them to be comparable to
  their full counterparts.  Previously, short and full domains were
  different, and dwgrep correspondingly gave warning when a comparison
  of the two was made.
Use brevity instead of bool in value::show