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.

winscw \fshell\build\s60\3rd_edition winscw udeb
armv5 \fshell\build\s60\3rd_edition armv5 urel