[TAP] Fix an artefact of 19026c1b.

TAPTable.copy(...) and TAPColumn.copy(...) use directly the attribute dbName
instead using getDBName() ; indeed getDBName() <> dbName.
Because of this bug, queries with aliased tables did not work anymore.

src/tap/metadata/TAPColumn.java

@@ -945,7 +945,7 @@ public class TAPColumn implements DBColumn {
 	@Override
 	public DBColumn copy(final String dbName, final String adqlName, final DBTable dbTable){
 		TAPColumn copy = new TAPColumn((adqlName == null) ? this.adqlName : adqlName, datatype, description, unit, ucd, utype);
-		copy.setDBName((dbName == null) ? this.dbName : dbName);
+		copy.setDBName((dbName == null) ? this.getDBName() : dbName);
 		copy.setTable(dbTable);
 
 		copy.setIndexed(indexed);

src/tap/metadata/TAPTable.java

@@ -1060,7 +1060,7 @@ public class TAPTable implements DBTable {
 	@Override
 	public DBTable copy(final String dbName, final String adqlName){
 		TAPTable copy = new TAPTable((adqlName == null) ? this.adqlName : adqlName);
-		copy.setDBName((dbName == null) ? this.dbName : dbName);
+		copy.setDBName((dbName == null) ? this.getDBName() : dbName);
 		copy.setSchema(schema);
 		Collection<TAPColumn> collColumns = columns.values();
 		for(TAPColumn col : collColumns)