Improved Modes

• improved mode handling (#59)
• add client.chanmode(channel, mode, target, network, fn) (target can also be an array)
• add client.voice(channel, nicks, network, fn) and client.devoice(channel, nicks, network, fn)
• add client.op(channel, nicks, network, fn) and client.deop(channel, nicks, network, fn)
• allow passing channels in network config
• updates to README.md
• remove unused dependency