code refactoring:
- Renamed CADSTAR_COMMON to CADSTAR_ARCHIVE_COMMON
- Renamed CPA_FILE to CADSTAR_PCB_ARCHIVE_PARSER
- Made CADSTAR_PCB_ARCHIVE_PARSER a derived class of CADSTAR_ARCHIVE_COMMON
- Moved all structures in cadstar_pcb_archive_parser.h/.cpp to be defined inside CADSTAR_PCB_ARCHIVE_PARSER class