Continuous Integration of RISC-V Testbenches

We have fixed many dozens of issues reported by Verissimo. Some were violations of our SystemVerilog/UVM coding guidelines that we previously had no automated way to detect, and some were due to rules we had not considered before. I especially like the rules that warn us about constructs that may work inconsistently on different simulators or that are not even supported on all simulators. It is important for our code to be vendor-neutral and portable.