[Nickle] autoload, autoimport, Ctype

[Bart Massey]

I've added (with Keith's help) a bit of stuff to the Nickle
distro that may be useful.

The autoload command
  autoload NamespaceXXXStuff;
looks for "namespace-xxxstuff.5c" on the (previously little-used)
library_path.  The autoimport command
  autoimport NamespaceXXXStuff;
autoloads the namespace if necessary, then imports it.

There is currently discussion about what the default library
path should be.  Suggestions are appreciated.

I've also added a builtin Ctype module, with the same
functionality as the C library version.  It also allows you
to define your own efficient ctype-like functions in terms
of a "characteristic function".  Ctype is ASCII-only: a
UCtype library is planned for Unicode compatibility, as soon
as I get around to it.

Note that no C code was harmed in the creation of these
modules: most new Nickle functionality can now be added in
Nickle.  This is a big win.

Comments and bug reports appreciated.

	Bart Massey
	bart@cs.pdx.edu