Added sf\3tshell platform with support for building beagle textshell+fshell ROMs.
As part of that:
* Added baserom command and tweaked it to be more friendly with SF baselines.
* Lots of build fixes
Also cd now makes sure the current working directory matches the file system with respect to case.
=head1 FShell Documentation
L<Introduction|fshell::commands::fshell/Introduction> - an introduction to fshell.
L<Getting started|getting_started> - a guide to getting fshell up and running on various different platforms.
L<Change History|fshell::change_history>
L<Core FShell functionality|core>
L<FShell Commands|commands> - an A to Z of all the commands that fshell supports.
L<Plug-ins|plugins>
L<Developer documentation|internal> - documentation for developers wishing to extend fshell or write new commands.