Review/fix/change file reassembly functionality.

- Re-arrange how some fa_file fields (e.g. source, connection info, mime
  type) get updated/set for consistency.

- Add more robust mechanisms for flushing the reassembly buffer.
  The goal being to report all gaps and deliveries to file analyzers
  regardless of the state of the reassembly buffer at the time it has to
  be flushed.

src/file_analysis/analyzer/extract/Extract.cc

@@ -68,7 +68,6 @@ static bool check_limit_exceeded(uint64 lim, uint64 depth, uint64 len, uint64* n
 		}
 	else if ( depth + len > lim )
 		{
-		printf("exceeded the maximum extraction lenght depth: %llu len: %llu lim: %llu\n", depth, len, lim);
 		*n = lim - depth;
 		return true;
 		}