Evaluate parens in refinement dispatch, ~10% speedup

[hostilefork]

The previous semi-hack of an evaluation trick so that get-words would
evaluate in paths has been upgraded to a much less hacky trick. This
now allows for the evaluation of parens to also be used to get the words
to use as refinements in dispatch:

>> append/(first [only])/(to-word "dup") [a b c] [d e] 2
== [a b c [d e] [d e]]

The method by which this is done--as well as reducing the number of
writes done into call frames--has improved performance in a build of
the hostilefork.com using the static builder by 10%. This means Ren/C
optimized non-debug builds are--for the first time--ever so slightly
faster than the rebolsource download (in that measurement).

[hostilefork]

Note that this commit had a somewhat naively-introduced bug with refinement ordering, where for something like a: func [x /b y /c z] would not treat a/b/c 1 2 3 and a/c/b 1 3 2 as equivalent calls

The impact on performance after the fix has not been measured yet after the fix (and there have been several other changes as part of the rewrite).