sanitize the graph of the system at every service parsing, remove -F option, force to use unsupervise command instead of -u at stop command

Tree rules, current directories are removed. This is known by the master resolve file of a tree.

Tree name directories are removed. Services are not dependent anymore of a tree.
Tree name directories are replaced by a unique services directory containing all services of the system with it resolve file.

Tree resolve file handle now the list of the service name to start with a tree.

This change give the services switch between trees easily without IO access by the simplication
of the research, access of the resolve file and script of a service.

This commit sign the end of the "[WIP] allow to switch between trees" works.
The tree directory was used with s6-rc. Tree are now completely handled by
resolve file. That's means that services are not independent of a tree.
Again earn of flexibility.