reverted back to original deck editor layout but including filtertree

the original layout is actually more space efficient if using CardFrame
instead of CardInfoWidget and reducing the size of the deck editor
toolbar.

this commit also removes the old search feature by removing the search
button and the clear search button. the clear search menu item is left
in place, however it now clears the filtertree.

finally, the stretch factor for the right frame in the main layout was
reduced to zero so that the card database gets priority for extra space.
this makes more sense because the deck editor does not actually need
very much horizontal space.

cockatrice/src/filtertree.cpp

@@ -328,3 +328,9 @@ bool FilterTree::acceptsCard(const CardInfo *info) const
 
 	return true;
 }
+
+void FilterTree::clear()
+{
+	while(childCount() > 0)
+		deleteAt(0);
+}