fix timestamp handling

As it turns out, the "local timestamp" as advertised by arcdps is a bit
misleading, because the timestamp is still in UTC. The "local" refers to
the fact that it can lag behind the server timestamp a bit (but usually
they seem to be within +-1 of each other), not that the timestamp is in
the local timezone.

This makes date handling a bit harder for raidgrep, but thanks to
chrono, not by much. The idea is that we simply deal with Utc pretty
much everywhere, except at the user boundary. This means that

1. Input timestamps for -before and -after are converted to Utc right
   after input
2. When outputting, we convert to a local timestamp first

This makes the output consistent with the filenames now (and the "wall
time" that the player saw).

0 files changed, 0 insertions, 0 deletions