logic to set up lrotdp from lpl.
lrotdp is .true. or .false. coresponding to calculate or
not to calculate a partial. the order of lrotdp (and also
of partial calculations) is as follows:
phi0, p, i0, psi0, mu, delta0, alpha0
pdot,a,b,c,d (terms added oct. 1978)
logic is as follows:
set all lrotdp that are specified by lpl
if any partial at all is desired, set lrotdp(1)
if partial wrt alpha0 or delta0 is desired, set lrotdp(3)
and lrotdp(4)
if partial wrt mu is desired, set lrotdp(3) and lrotdp(4)

set up vector lpl, internal to rotlog, which indicates
the parameters for which partials calculations are
needed. construction of lpl depends on ict(4), iabs1,
and mpl vector.