Comment unreachable rules

Continuous signals have less priority than inputs. Therefore before
evaluating them it is mandatory to check the presence of messages in the
input queue of the SDL process. User has to provide the function that
checks the queue. TASTE uses POHIC API for that.

- an extra "end if" was generated in some cases when using continuous
  signals
- when generating the simulation script, lower the process name as gnat
  generates only lowercase .o files