Permit special field in paths passed to OS_CLI
OS_CLI permits commands to be prefixed with a temporary filing
system, for example
It also passes commands unrecognised to FileSwitch to be executed,
ADFS::HardDisc4.$.!Boot first sets the temporary filing to
ADFS then executes
This does not work if the path contains a special field, currently this results in an error as the special filed would be lost.
Unfortunately many programs, including the RISC OS source fail because of this.
Instead if a filing system prefix with special field
is found switch to the Temporary filing system and
treat the whole command as a path to execute. For example
IXFS#W:$.HardDisc4.!Boot sets the temporary filing
IXFS then executes