CFS_WRITE implies O_TRUNC which is implemented on CBM DOS by deleting an
exsisting file. Hoewever this succeeds only if the CBM DOS filetype matches.
We need a working O_TRUNC in order to be able to overwrite the contiki.cfg
configuration file.
Note: Now it has be clarified why overwriting the configuration file started to
fail the CBM PFS (platform file system) can be activated for the recently added
ethconfig program.
Better match user expectations by allowing to download plain disk images and configure the IP settings afterwards on the target machine - then most likely leveraging DHCP. This works for the users with the most usual Ethernet adapter and settings - which are now pre-configured in default.cfg's. Only the few users with non-default Ethernet adapter and/or settings are required to download a custom contiki.cfg and inject it manually into their disk image files.
This additional application results in three disks for the Apple2, two disks for the C64 and one disk for the C128. Therefore the download page can't get along anymore without some JavaScript adjusting the number of downloadable disks depending on the selected machine. With JavaScript turned off access to non-existent disks (i.e. disk 3 for the C64) results in a successfull download of a zero byte sized file - not exactly great but at least a defined behaviour.
