NAME
        IsFileSystem -- returns whether a Dos handler is a filesystem (V36)

   SYNOPSIS
        result = IsFileSystem(name)
        D0                     D1

        bool isfilesystem(strptr)

   FUNCTION
        Returns whether the device is a filesystem or not.  A filesystem
        supports seperate files storing information.  It may also support
        sub-directories, but is not required to.  If the filesystem doesn't
        support this new packet, IsFileSystem() will use Lock(":",...) as
        an indicator.

   INPUTS
        name   - Name of device in question, with trailing ':'.

   RESULT
        result - Flag to indicate if device is a file system

   SEE ALSO
        lock()