Foremost a fix for SmTreeModel

Not working again, but I eventually have to commit the changes. Fixes to
SmTreeModel:

* Fix SmTreeModel::index(). The previous comment was quite valid. I'm
surprised that it worked at all. I have no clue why to return an invalid
QModelIndex if the column isn't 0. Now an index with any valid column
number can be created.

* Fix SmTreeModel::parent(). Again, why shouldn't we create a parent
index with a column other than 0? No idea...

* Fix SmTreeModel::headerData(). Add some sanity checks.

* Fix SmTreeModel::findRecursive(). Well, what is there to say. It never
worked for models with a depth > 1, but obviously it didn't really
matter until now. To make it work I had to change SmTreeItem as well.
SmTreeItem::next() returns the next valid parent/sibling, or 0 if there
isn't one.

There may be some fallout from these changes, but they're yet to be
seen.

Changes to PictureView:
* fix selecting an item according to the new datasbase layout
* same goes for editing items. If an update actually works has to be
checked.

Overall, it's an intermediate commit that should have been a sane series
of commits. Can't be changed now...

1 files changed, 3 insertions, 0 deletions

diff --git a/seriestreemodel.cpp b/seriestreemodel.cpp
index 2319c51..c8260c4 100644
--- a/seriestreemodel.cpp
+++ b/seriestreemodel.cpp
@@ -526,6 +526,9 @@ void SeriesTreeModel::readSettings(){
 }
 
 void SeriesTreeModel::conditionalUpdate(const QModelIndex &parent, int field, const QVariant &value){
+    if(!parent.isValid()){
+        return;
+    }
 	SmTreeItem *item = static_cast<SmTreeItem*>(parent.internalPointer());
 	if(item->childCount() > 0){
 		//series