Option to read timestamps from data (CLF)

[flaupretre]

An option which would cause timestamps to be read from the input log lines (supposed to be in Common Log Format). Would allow running old logfiles through managelogs using time-related features.

The logmanager library is already prepared for such a feature as timestamps are sent as function arguments everywhere. Teh current version of managelogs always sends a null value, meaning that the library gets the time from the system clock. So, we just need the code to extract the time from each log line.

Format can even be auto-recognized (recognition code to be inspired from the same feature in analog or summary).