In commands, gather up option values first, and check for errors.  If there
    is an error in an option specification, return before messing with the
    object.  Otherwise, go ahead and mess with the object.
Evaluate maxlon and minlon correctly when reading in lat-lons (polar regions),
    or provide for explicit input of maxlon and minlon (which could be set to
    bogus).
Add flag to GeoLnArrToMap that does not worry about segments if just drawing
    points.
Create C functions for arithmetic on angles that check for "overflow."
Restore Sinusoidal projection (or install some other global equal area
    projection).
Option to make geomap::lnarr fmbin and fmxdr read double precision.
Decide if Add*Task and Cnx*Task functions should return success code instead of
    void.
Retire gaz@tkgeomap.org
Optimize the calculations that use spherical trigonometry.
Make geolinearray and maplinearray structures resemble each other.  If
projection is cylindrical equidistant, skip maplinearray transformation to
save memory.