Add speed optimization options to libCompiler

2 new compiler options for optimizing Java VM:
* `d32: true` -> `java -client -d32`
* `TieredCompilation: true` -> `java -server -XX:+TieredCompilation`

Further to #2

I think this is all that's needed (apart from documenting). To my surprise, my tests so far show that d32 is faster on my machine than TieredCompilation, though this probably depends not only on the machine/environment, but also on the size/complication of the compilation. I'd suggest pushing this, and then getting other people to try out on a variety of machines. If there's a clear pattern, recommendations can then be made in the docs. As these are extra options, there should be no bc issues.