add FindEvsql/FindLibPQ cmake modules and irc_log.sql definition, and implement logging of JOIN, PART, MODE, TOPIC, KICK, PRIVMSG, NOTICE and OPEN messages
CREATE TABLE logs (
id serial,
network varchar(32) NOT NULL,
channel varchar(32) NOT NULL,
ts timestamp with time zone NOT NULL DEFAULT CURRENT_TIMESTAMP, -- UTC time
nickname varchar(32), -- source nickname, NULL for "meta" events
username varchar(32), -- source username, NULL for "meta" events
hostname varchar(64), -- source hostname, NULL for "meta" events
type varchar(16) NOT NULL, -- event type
target varchar(32), -- optional target
message varchar(512) -- optional event data
);