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.
An fshell command uses a CIF file.
DESCRIPTION: short description of the command (for the .cif file)