Support drop-columns using brackets (Oracle syntax style)

E.g. 
  alter table test drop (a, b) 
works same as  
  alter table test drop column a, b 

h2/src/main/org/h2/command/Parser.java

@@ -6073,6 +6073,7 @@ public class Parser {
                 command.setType(CommandInterface.ALTER_TABLE_DROP_COLUMN);
                 ArrayList<Column> columnsToRemove = New.arrayList();
                 Table table = tableIfTableExists(schema, tableName, ifTableExists);
+                readIf("("); // For Oracle compatibility - open bracket required
                 do {
                     String columnName = readColumnIdentifier();
                     if (table == null) {
@@ -6084,6 +6085,7 @@ public class Parser {
                     Column column = table.getColumn(columnName);
                     columnsToRemove.add(column);
                 } while (readIf(","));
+                readIf(")"); // Fro Oracle compatibility - close bracket
                 command.setTableName(tableName);
                 command.setIfTableExists(ifTableExists);
                 command.setColumnsToRemove(columnsToRemove);

h2/src/test/org/h2/test/db/TestAlter.java

@@ -116,7 +116,13 @@ public class TestAlter extends TestBase {
         stat.execute("create table test(id int, name varchar, name2 varchar)");
         stat.execute("alter table test drop column name, name2");
         stat.execute("drop table test");
-
+        // Test-Case: Same as above but using brackets (Oracle style)
+        stat.execute("create table test(id int, name varchar, name2 varchar)");
+        stat.execute("alter table test drop column (name, name2)");
+        assertThrows(ErrorCode.COLUMN_NOT_FOUND_1, stat).
+            execute("alter table test drop column name");
+        stat.execute("drop table test");
+        // Test-Case: Error if dropping all columns 
         stat.execute("create table test(id int, name varchar, name2 varchar)");
         assertThrows(ErrorCode.CANNOT_DROP_LAST_COLUMN, stat).
             execute("alter table test drop column id, name, name2");
@@ -209,6 +215,8 @@ public class TestAlter extends TestBase {
         stat.execute("drop table t");
     }
 
+
+    
     // column and field names must be upper-case due to getMetaData sensitivity
     private void testAlterTableAddMultipleColumnsBefore() throws SQLException {
         stat.execute("create table T(X varchar)");