object class for planar difference sets

Changes for 1.001 - 2023-12-23T08:34:04+01:00

• improved zeta/theta calculation
• revised examples suite:
• - extended pds_info
• - fixed filter mode of pds_planes
• - merged random_pds into pds_sample
• - fixed exit code of pds_verify (++Lukas Mai)
• added another computing example
• minor edits in documentation