This will make adding a compiled wrapper easier during transition.

We don't compile any code yet.  This is just the framework split
out for easier review.  We'll start compiling things in follow up
commits.

For now, we wrap the existing shell script to maintain full compat.
We'll start moving over functionality in pieces so we can test.

We don't have any tests here yet, but provides the basic framework
for adding them.  The test runner can link & run fine though.

Tests are written using Google Test (gtest) and in C++ to make our
lives easier with more powerful data structures.

These will be used whenever we need to allocate memory and abort if
it fails for any reason.

We work with a few sets, so add a data structure for it to avoid
ad-hoc implementations in other modules.  This is simplify a list
as the sets we're working with tends to be quite small: typically
less than 10.  As long as we don't need to support more, the perf
should be good enough.

The shell script is no longer responsible for parsing the command
line at all.

This is needed for newer gcc versions.