tell user when setting logpath
implement requesting logs on a per-network module level
e.g. /msg *backlog #helloworld 42

currently needs the LogPath variable set to an absolute filesystem path
in order to function at all
e.g. /msg *backlog LogPath /home/me/.znc/users/$USER/moddata/log/$USER_$NETWORK_$WINDOW_*.log

filenames are matched to the last asterisk '*' character in the LogPath.

$USER, $NETWORK and $WINDOW are substituted as following:
$USER: your ZNC username
$NETWORK: the network that the module was loaded on
$WINDOW: requested window name (/msg *backlog $WINDOW)

if line count is omitted, it defaults to 50