These commands behave as DEL and SET (blindly Remove or Overwrite) when
they don't get IF* flags, and require the value of the key when they do
run with these flags.
Making sure they have the VARIABLE_FLAGS flag, and getKeysProc that can
provide the right flags depending on the arguments used. (the plain
flags when arguments are unknown are the common denominator ones)
Move lookupKey call in DELEX to avoid double lookup, which also means
(some, namely arity) syntax errors are checked (and reported) before
checking the existence of the key.
0a6eacff1f