cvise reimplements creduce in Python and bundles clang-delta and other
tools. In my experience, it is generally a more robust reduction tool
that is better maintained. I renamed the script to make it tool-neutral,
which also opens up the possibility that we teach it how to
automatically transition over to llvm-reduce and opt/llc to handle LLVM
backend crashes, but that is potential future work.
Internally, the variable names still say "creduce". I kept using the
verb "reduce" because "vise" is not a verb, but the external facing text
has been updated.
