http_ms now a DOUBLE

Accept log entries with DOUBLE in http_ms and insert into MySQL.
Rewrite [headers] filter to save all values

Save all headers seen and compare for changes.
[dns] better message
Detect lowercase 'location:' header

Detect ‘location:’ and ‘Location:’ headers properly. Some malware
doesn’t capitalize it.
Truncate http_ms to milliseconds

Truncate http_ms to milliseconds when creating a CSV/TSV for D3 to use.
That’s enough accuracy for Internet times. Also may save some
javascript time in D3 charts.