the integration control integer array 'kp' is examined to see
if i.c. partial number 'l' exists.  if so, tape ptr 'kplnt'
and kp ptr 'lplnt' are updated, and control returns.
'iswtch' indicates whether the corresponding observation
partial can be copied from saved values (1 if so, 0 if not).
if the partial exists neither place then the offending body and
kp are printed and processing halted.  if the partial was not
integrated but can be copied, then iswtch is set equal to -1
and control returns.
note: 'iq2' is a 2-letter abbreviation for the body.
special values for klak: -3 earth-moon barycenter,
-2 moon
-1 earth rotation
0 moon rotation