Previously it seems to have worked by accident (there was not enough
space for the end NULL byte).

This allows adding of new commands without any changes to command
parsing and generation code.

After sending command to videohub the response must read before
another commands is sent.

This prints the device configuration as videohubctrl parameters thus
allowing the configuration to be restored later.

Add support for setting video input/output names, video output locking
and video output routing.

Show port numbers next to inputs and outputs and locks next to
outputs to better reflect the logic for their manipulation.

Now the short parameter is the first letter of the long parameter
which is much more natural.

The short -h parameter will be used to set device host name.

It is not a good idea parse_cmd() to just die().

It is not guaranteed that each command will come in it's own buffer. In
fact when several changes are made at once the commands are not separated.

The routing was completely reversed and buggy. It should be done by
output instead it was done by input.