Added tests for \KsPdo\DbTable::__construct(), \KsPdo\DbTable::setFieldMeta(), \KsPdo\DbTable::getFieldMeta(), \KsPdo\DbTable::getFieldList(), \KsPdo\DbTable::getMainSqlPart() methods
Refactoring: extract methods \KsPdo\DbTable::getFieldsRealWithTblDotPrefix() and \KsPdo\DbTable::getVirtualFieldsWithAliasDotPrefix() from \KsPdo\DbTable::getFieldsRealAndVirtual()
Added tests for KsPdo\DbTable::getVirtualFields() and KsPdo\DbTable::addVirtualField() methods