use FastISODateParser.parseAsEpochMilli

Compared to FastISODateParser.parse, which returns an
OffsetDateTime object, parseAsEpochMilli returns the
epoch time millis. The performance improvement for
date parsing alone is roughly 100% (8m dates/s to
18m dates/s).
Insertion speed improved from 13-14s for 1.6m entries
to 11.5-12.5s.

pdb-ui/src/main/java/org/lucares/pdbui/date/FastISODateParser.java

@@ -47,7 +47,7 @@ public class FastISODateParser {
 		}
 	}
 
-	public long parseAsTimestamp(final String date) {
+	public long parseAsEpochMilli(final String date) {
 		try {
 //			final long year = Integer.parseInt(date, 0, 4, 10);
 //			final long month = Integer.parseInt(date, 5, 7, 10);