common: Improve logger configuration

common: Improve logger configuration

Initialize logging earlier, so output during core initialization
gets routed properly.

Enable the logging options also for quasselclient; there's no good
reason to limit this to the core and monolithic client. However, as
a side-effect, the default log level is now Info also for the client,
so "-l Debug" must be specified on the command line to get debug
output.