m.e.ash  march 1968  subroutine planet
main program for n-body, earth-moon barycenter, planet-asteroid,
and satellite-probe numerical integrations
kfit=0 integrations are in midst of orbit fitting iterations
kfit=1 integrations are after orbit fitting convergence, extend
integration interval without partials, change output tape
updated feb. 1980   kcl: tcon added

kkp(96)=   number of days from epoch in first time direction
for reintegration of equations of motion after orbit
convergence
kkp(97)= 0 no partials integrated in reintegration of equations of
motion after orbit fit convergence
kkp(97)= 1 partials are integrated in reintegration of equations of
motion after orbit fit convergence
kkp(98)=   number of days from epoch in second time direction
for reintegration of equations of motion after orbit fit
convergence
kkp(99)=   output tape number for reintegration of equations of motion
after orbit fit convergence if jct(79)=1