Added MCommandExtensionsV1 as an extensible way of adding new virtual functions to CCommandBase without breaking BC.
Using this, added a custom error code resolver and added lots of Software Install errors to swi.
Fixing some epocroot build issues. Added tefcons for hooking fshell into TestExecute.
Also removed a bunch of duplicate def files.
Fixed fshell.bat so that the emulator starts with platsec switched on.