Add method to obtain main_time and define function sc_time_stamp() - …

Although this is only required if we emit something requiring a time stamp, we may as well do it all the time. Determining when it would be required could be problematic, and we should minimize differences in generated emulations.

but generate different test-benches for gate-level simulation

Added GCDSpec which does GCD but uses peek poke tester
Changed router to not be ignored, it works for me
Fixed style errors in string interpolation