fix construct in vtlib base module code.

In Construct function we have tu use the class name, not
the currentModule global variable.
We can have the case that from an other module call to a related module without retrive_entity_info,
and try to call getColumnFields(With a incorrect module name).

vtlib/ModuleDir/ModuleFile.php

@@ -94,12 +94,13 @@ class ModuleClass extends CRMEntity {
 	var $mandatory_fields = Array('createdtime', 'modifiedtime', 'payslipname');
 
 	function __construct() {
-		global $log, $currentModule;
-		$this->column_fields = getColumnFields($currentModule);
+		global $log;
+		$this_module = get_class($this);
+		$this->column_fields = getColumnFields($this_module);
 		$this->db = PearDatabase::getInstance();
 		$this->log = $log;
 		$sql = 'SELECT 1 FROM vtiger_field WHERE uitype=69 and tabid = ?';
-		$tabid = getTabid($currentModule);
+		$tabid = getTabid($this_module);
 		$result = $this->db->pquery($sql, array($tabid));
 		if ($result and $this->db->num_rows($result)==1) {
 			$this->HasDirectImageField = true;