Added the message and strings files

message.clp contains the message template

strings.clp contains helper string functions
Added shell.clp - used for accessing the electron shell
Removed the os/os.clp load

I don't want to implement this feature yet.
Added the electron shell script

This script makes it really easy to run different expert systems loaded into
the file system
Rewrote the filesystem handlers to use a far more elegant system

It is now far easier to build file system paths (no need to use the format
command anymore) as well as maintain readability (a huge factor in this
change). I have updated logic/shell.clp, etc/skel/bootstrap.clp, and
etc/sys.clp. The new filesystem handlers are methods of the form
/etc, /lib, /data, etc. These functions make it possible to build up paths
without sacrificing readability :D.