add sanity check for `PMEDM` inputs

[jGaboardi]

• add sanity check for PMEDM inputs à la pmedm_legacy
• xref
  • strict positional vs. keyword arguments – pymedm #16
  • make individual repo tickets for #15 -- strict positional vs. keyword arguments likeness-vitals#26
  • comb through - clean up internal positional vs. keyword arguments likeness-vitals#15