		Loadable C extensions

Tcl lets you augment the language with commands written in C. This
gives added speed and the ability to handle binary data. I will be
providing more and more loadable versions of bits of zircon as time
goes on so I would appreciate some feedback from people on how to
create them on different systems.

Currently the only loadable module is in the directory plugins/Sed.
On Solaris I give the commands :

gcc -c -fPic sed.c
ld -G -z text -o libSed.so sed.o

And this creates me the library libSed.so I then run tclsh
and give the commands :

pkg_mkIndex . *.tcl *.so
exit

This will pick up the loadable module whcih will be used in preference
to the tcl version which uses a helper program.

I don;t know how to do this on any other system other than Solaris so
I cant do a Makefile just yet - so let me know how its done on your
system!!

Thanks

L.
