adjust amused-monitor not to query amused on certain events but use the new extra info that `amused monitor' prints.

round() rouds towards infinity, but for the line counting i need a round towards zero, the one provided by int()

adjust the index before reordering the entries, otherwise we may try to read out-of-bound because the reading loop wraps at $lines, not at $tmp size.

`amused monitor' defaults to report all the events, that should be enough.

instead of passing "half" of the context wanted, just take the number of lines wanted. switch to a circular buffer to store the lines instead of shelling out (badly) to grep -C.