This PR adds the jobs argument to inform CACE about number of jobs needed to run a certain tool. This is necessary to prevent too many parameters being spawned that require more hardware threads than are available.
The jobs argument is implemented for the ngspice and klayout_drc tool.

Two other arguments, drc_script_path and spiceinit_path were implemented.

• ngspice tool:
  • Add jobs argument
  • Add spiceinit_path argument
  • By default copy the PDK spiceinit to the simulation directory
• klayout_drc tool:
  • Add jobs argument
  • Add drc_script_path argument
• Reserved variables:
  • Add CACE{jobs}
  • Add CACE{root}
• Issue a warning when a conditions has the same name as a reserved variable