logging: cli options to filter for modules using -v

old style "-v" still works

filtering examples:
-v=debug,network=error,interface=error      // effectively blacklists network and interface
-v=warning,network=debug,interface=debug    // effectively whitelists network and interface

electrum/network.py

@@ -223,7 +223,6 @@ class Network(Logger):
     """The Network class manages a set of connections to remote electrum
     servers, each connected socket is handled by an Interface() object.
     """
-    verbosity_filter = 'n'
 
     def __init__(self, config: SimpleConfig=None):
         global INSTANCE