Add a helper to connect to Xpra inside the Docker container

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Get rid of startup.sh

We really can do almost all of it in the Dockerfile. The only thing we cannot do there is the password generation; The plan is to move away from the password anyway, in favor of a to-be-generated private/public key pair.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Switch to a seamless desktop

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Start the Xpra server when starting the container

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
connect.sh: do not complain about unknown host key

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Start ssh daemon first and keep Xpra in the foreground

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Adjust README

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>