Add --irconly, --gitonly and --who and remove --format

Three new arguments are added.  The '--who' argument is to filter for a
given irc nickname, so it's easy to search for IRC logs from a specific
person.

The --irconly and --gitonly are here so we can skip one source if we
don't need it.

The --format was useless for now.
No need to pass who as an argument

we can get it via *who
Simplify the filter "who"
add --search argument

Display only items that match the value of the --search argument.