libpms API is missing some features available via command-line

[vasdommes]

The following settings are available as command-line options for mpsolve executable, but are missing from libmps API:

 -j n        Number of threads to spawn as workers
 -S set      Restrict the search set for the roots
             set can be one of:
               u: upper half-plane { x | Im(x) > 0 }
               d: lower half-plane { x | Im(x) < 0 }
               l: left half-plane { x | Re(x) < 0 }
               r: right half-plane { x | Re(x) > 0 }
               i: inside the unit circle: { x | |x| < 1 }
               o: outside the unit circle { x | |x| > 1 }
               R: real axis { x | Im(x) = 0 }
               I: imaginary axis { x | Re(x) = 0 }
 -D detect   Detect properties of the roots:
               r: real roots
               i: imaginary roots
               b: both
 -s file     Read the starting approximations from the given file, instead
             of relying on the internal algorithm of MPSolve.
             The format for this file is the same of the *.res files foun in
             src/unisolve/*.res in the source distribution of MPSolve.