This is a language plugin for GGobi which embeds the Perl interpreter
inside GGobi and allows developers to create others plugins written in
Perl for GGobi.  The motivation is that this will be useful for
creating specialized input plugins for reading data from different
formats since Perl is exceedingly good at this.

Additionally, since there exist Perl bindings for Gtk, one can create
regular UI plugins for GGobi in a higher-level language than C, and
not necessarily have to use R.

When we migrate the GGobi data structures to being regular Gtk objects
(reasonably soon now), then we will be able to have easy access from
Perl to Gtk events, data structures, etc.  Given this, a Perl plugin
will be able to readily interact extensively with GGobi.

As of now, we need a few more hooks and Perl bindings for GGobi to
make this interface work well. These will emerge gradually, or perhaps
we may use SWIG or Slcc to generate them.  Having this plugin
mechanism will hopefully encourage others to push to have the
bindings, or maybe even add them themselves.

