only switch after the save of trees information, do not destroy the temporary db in case of crash: this will leave the running db in inconsistent state

adds field @extdepends. Services declared with @optsdepends are not mandatory. Services declared with @extdepends must have the frontend file installed at least

make a distinction between system error and unable to find the service, return -1 on system error, 0 for service error

Bugs fix: set uid array to zero, retrieve the old behavior at unsupervise proccess and do not die if we can't stop services properly