Improve toXML demo to get parameters of function call

[sqlparser]

Oracle query

BEGIN 
SELECT * FROM test123.TableOK; CALL fnc.copy_table('test234.test1','test567test2'); CALL fnc.copy_table('test345.test3','test678.test4'); SELECT * FROM test456.test5 a INNER JOIN test789.test6 b ON a.rowid = b.rowid; 
END

https://github.com/sqlparser/gsp_demo/tree/master/dotnet/src/demos/visitors

[cnfree]

Implemented it.

但是 http://www.sqlparser.com/xml/sqlschema/doc/sqlschema_xsd.html 并没有 TCallStatement 的schema，参照open_statement实现的，但是 Call Statement 比 Open Statement复杂很多。