Directories are handled by sanitize_write

Module and bundle should only know about services inside its.
Spawn a new process with its own graph when dealing with module/bundle services.

Do not write the resolve file itself.
move contents and ncontents from regex to dependencies addon struct

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.

Thanks for your service! This resolve file was used with s6-rc. The things now are simplier
and flexible.