(compiler) Add `class` support
At last, after almost 5 years of development, it's finally happening. Classes are making their way (back) into the Perlang language, now that we both:
- need them, and
- have a good way to represent them in the underlying compiled output
The latter part is kind of obvious. Since we are compiling Perlang to C++, the natural representation in the compiled form is to match Perlang classes 1-to-1 with C++ classes. This also makes a lot of sense in our current interop approach; by exposing Perlang classes as C++ classes, we should be able to use them from C# reasonably seamlessly, or that's the idea at least.
Closes: #66 (closed)