db class for PrimEx

• Handles MySQL connection for PrimEx software
• Instantiated with default database
• Checks for existing connection: one connection to db server
• Respects PRIMEX_CALDB_HOST environment variable
• db.h
• Used by cluster_info class (hycal library) and calib_manager/calib_connect.c
  • cluster_info.cc
  • calib_connect.c
  • get_handle.cc