Replace post-increment on iterators with pre-increment

This is a micro-optimization, as pre-increment is at least as efficient
as post-increment and typically slightly more so because it doesn't need
to make a copy of the iterator, and better conforms to the prevailing
C++ style.

Closes https://github.com/wxWidgets/wxWidgets/pull/655

src/common/datavcmn.cpp

@@ -2734,7 +2734,7 @@ unsigned int wxDataViewTreeStore::GetChildren( const wxDataViewItem &item, wxDat
     if (!node) return 0;
 
     wxDataViewTreeStoreNodeList::iterator iter;
-    for (iter = node->GetChildren().begin(); iter != node->GetChildren().end(); iter++)
+    for (iter = node->GetChildren().begin(); iter != node->GetChildren().end(); ++iter)
     {
         wxDataViewTreeStoreNode* child = *iter;
         children.Add( child->GetItem() );
@@ -2939,7 +2939,7 @@ void wxDataViewTreeCtrl::DeleteChildren( const wxDataViewItem& item )
 
     wxDataViewItemArray array;
     wxDataViewTreeStoreNodeList::iterator iter;
-    for (iter = node->GetChildren().begin(); iter != node->GetChildren().end(); iter++)
+    for (iter = node->GetChildren().begin(); iter != node->GetChildren().end(); ++iter)
     {
         wxDataViewTreeStoreNode* child = *iter;
         array.Add( child->GetItem() );

src/common/menucmn.cpp

@@ -982,7 +982,7 @@ wxMenuItem *wxMenuBarBase::FindItem(int itemid, wxMenu **menu) const
     wxMenuItem *item = NULL;
     size_t count = GetMenuCount(), i;
     wxMenuList::const_iterator it;
-    for ( i = 0, it = m_menus.begin(); !item && (i < count); i++, it++ )
+    for ( i = 0, it = m_menus.begin(); !item && (i < count); i++, ++it )
     {
         item = (*it)->FindItem(itemid, menu);
     }

src/common/tarstrm.cpp

@@ -903,7 +903,7 @@ wxTarNumber wxTarInputStream::GetHeaderNumber(int id) const
         wxTarNumber n = 0;
         wxString::const_iterator p = value.begin();
         while (p != value.end() && *p == ' ')
-            p++;
+            ++p;
         while (isdigit(*p))
             n = n * 10 + (*p++ - '0');
         return n;

src/generic/datavgen.cpp

@@ -3654,7 +3654,7 @@ public:
 
         if( node->GetItem() == *m_iter )
         {
-            m_iter++;
+            ++m_iter;
             return DoJob::CONTINUE;
         }
         else

src/generic/notifmsgg.cpp

@@ -327,7 +327,7 @@ void wxNotificationMessageWindow::AddVisibleNotification(wxNotificationMessageWi
 {
     bool found = false;
     for ( wxVector<wxNotificationMessageWindow*>::iterator it = ms_visibleNotifications.begin();
-        it != ms_visibleNotifications.end(); it++ )
+        it != ms_visibleNotifications.end(); ++it )
     {
         if ( *it == notif )
         {
@@ -345,7 +345,7 @@ void wxNotificationMessageWindow::AddVisibleNotification(wxNotificationMessageWi
 void wxNotificationMessageWindow::RemoveVisibleNotification(wxNotificationMessageWindow* notif)
 {
     for ( wxVector<wxNotificationMessageWindow*>::iterator it = ms_visibleNotifications.begin();
-        it != ms_visibleNotifications.end(); it++ )
+        it != ms_visibleNotifications.end(); ++it )
     {
         if ( *it == notif )
         {

src/msw/menu.cpp

@@ -1195,7 +1195,7 @@ void wxMenuBar::RebuildAccelTable()
     size_t nAccelCount = 0;
     size_t i, count = GetMenuCount();
     wxMenuList::iterator it;
-    for ( i = 0, it = m_menus.begin(); i < count; i++, it++ )
+    for ( i = 0, it = m_menus.begin(); i < count; i++, ++it )
     {
         nAccelCount += (*it)->GetAccelCount();
     }
@@ -1205,7 +1205,7 @@ void wxMenuBar::RebuildAccelTable()
         wxAcceleratorEntry *accelEntries = new wxAcceleratorEntry[nAccelCount];
 
         nAccelCount = 0;
-        for ( i = 0, it = m_menus.begin(); i < count; i++, it++ )
+        for ( i = 0, it = m_menus.begin(); i < count; i++, ++it )
         {
             nAccelCount += (*it)->CopyAccels(&accelEntries[nAccelCount]);
         }