add query completion

We are using ANTLR listeners to find out where in the
query the cursor is. Then we generate a list of keys/values
that might fit at that position. With that information we
can generate new queries and sort them by the number
of results they yield.

performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java

@@ -5,7 +5,6 @@ import java.nio.file.Path;
 import java.time.OffsetDateTime;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
@@ -190,9 +189,7 @@ public class PerformanceDb implements AutoCloseable {
 
 	public List<Proposal> autocomplete(final String query, final int caretIndex) {
 
-		// TODO implement proposals
-		// return db.proposeTagForQuery(query, caretIndex);
-		return Collections.emptyList();
+		return db.propose(query, caretIndex);
 	}
 
 	public List<String> getFields() {