Implement Delete operation in AccountPanel contextual menu

Fix a bug in a SQL request
Use nbCategories in AccountPanel to prevent buffer overflow

src/view/grid/DateDelegate.cpp

@@ -21,16 +21,13 @@
 
 #include "DateDelegate.hpp"
 
-#include <iostream>
-
 QWidget * DateDelegate::createEditor (QWidget * parent, const QStyleOptionViewItem & option, const QModelIndex & index ) const
 {
     QComboBox* combo = new QComboBox(parent);
     QDate date(_year, _month, _day);
-    QString s;
 
     for(int i=0; i<date.daysInMonth(); i++)
-    	combo->addItem(s.sprintf("%d", i+1));
+    	combo->addItem(QString::number(i+1));
 
     return combo;
 }