[WIP] Initial work on integating cmaes.

I started integrating CMAES into Simbody. Right now, everything is in quite a mess.

My objectives with this PR are:

- [x] Get basic CMAES functionality going.
- [x] Get the existing test cases to work (Rosenbrock, Schwefel, etc.).
- [x] cmaes readpara_t settings (e.g., convergence).
- [x] Diagnostics levels and file writing
- ~~[ ] Resuming.~~
- [x] Nice documentation about CMAES in Optimizer.h, describing possible settings.
- [x] No memory leaks.
- [x] Rewrite the test using `SimTK_TEST_` macros.
- [x] Replace abs with SimTK::abs.
- [x] Incorporate @nikohansen's updates to c-cmaes (cmaes_init_final).
- [x] In doxygen, mention that the errcmaes.dat file will be written regardless of the diagnostics level.
- ~~[ ] When to throw an exception upon failure?~~

This PR is going into the `cmaes-features` branch. There's much more to come, such as threading. However, to make this work manageable, those additions will come in subsequent PR's (still into the `cmaes-feature` branch).
> Or, he could make compilation of those functions optional, controlled by some compile-time symbol that we could unset.

This code is optional; there is no coupling between the boundary_transformation files and the cmaes files. If we just remove them, your concern is that someone else will eventually copy them in again?



> I don't know what these boundary_ functions are for, but is it conceivable that you or someone else might want to extend the Simbody CMAES functionality some day to include those functions?

I've read through the documentation for the boundary_transformation stuff. I think it helps when your parameters span a large range of values. In Jack/Tim's code, they scale/unscale parameters outside of the optimizer. I think it is unlikely that we will decide to use it. I'd like to keep our usage of cmaes fairly simple; I've already made it more complex than Jack had it.

My preference is to just omit those files, since it's unlikely we'll use them (they are a newer addition to Niko's code, I think. I think when Jack got the code a few years ago the boundary_transformation files weren't part of the code). But just say the word, and I'll start talking to Niko. In the mean time, I've removed the files.