Don't use __sighandler_t at all, it is not standard and at least on
DrgaonFly means something completely different. Also change the typedef
to match what signal actually expects. Fix some more minor glitches
for DragonFly.
Xfractint draws a wide variety of fractals. Xfractint is a port of the
IBM PC program fractint. Xfractint has online documentation which
should be referenced for most operation information. Note that the
online documentation is from fractint, and does not always accurately
describe xfractint.
