remove function about backup handling: the backup directory is now handled completely differently without the use of s6-rc

change graph_build_g interface, add graph_build_g, graph_build_service, graph_build_service_bytree_from_src function

service Master resolve file is no longer a service incorporate to the DB. It was reorganize to provide mandatory field to be a real Master. This file will now be used to known the global state of the services.

add resolve_modify_field and resolve_modify_field_g function. Rename SERVICE_STRUCT and TREE_STRUCT to DATA_SERVICE and DATA_TREE respectively

rename field deps to depends and ndeps to ndepends, add requiredby and nrequiredby field. Change interface of service_resolve_sort_bytype. Add service_resolve_create_master function

add tree_resolve_create_master, tree_resolve_modify_field, tree_resolve_field_tosa, tree_iscurrent, tree_isinitialized, tree_isenabled and tree_ongroups function

revamp of the info_walk, info_graph_init and info_graph_display function. Add info_graph_service function

rename service_resolve_svtree function to service_intree. Rename struct ss_resolve_graph_style to info_graph_style

complete reframe of resolve API function: allow to use different struct of resolve in function of the object to deal with. Split service and tree resolve function to separated file.