Revised version of arc2trig, using the new libsrc routines read_arc.c.

Note that writetrig.c was previously labeled as "multi-thread safe". In fact,
it is NOT multi-thread safe, since it stores values in static variables that
are not protected by mutexes. Since I don't know of any multithread
applications for writetrig.c, I have simply corrected the comment at the top
of the source file.

Pete Lombard, 12/11/98
