Use full set of syslog severity levels

[xiongchiamiov]

Unwittingly, I designed Alertinator to use a subset of syslog's severity levels (defined in rfc5424). It seems reasonable to support the full set.

It does seem like perhaps a bit much, though - not only will users need to determine which alert level is appropriate, but it makes user config more complex, particularly since we don't have a good way of specifying "this level and up".

[entendu]

particularly since we don't have a good way of specifying "this level and up".

We do -- that's the beauty of the bitmask. With the 3 levels you have today, reporting all except Critical would be ALL & ~CRITICAL. "Warning and up" could be ALL & ~NOTICE or WARNING | CRITICAL.

👍 to this idea.