different delete (-) behavior for node that has only one child

[stengel]

If one clicks "delete" on a node with a single child, the node itself should be removed by now creating a direct line from the parent to the child. The current behavior is to remove the child and its subtree. So here the subtree would be kept intact but become the child of the parent of the node of the deleted node, reached by the move name from the parent node. What would be removed is the node and its single outgoing move.

If the node is in an information set, then all nodes in that information set must have the same number of moves, in this case a single move.
At the moment, any "delete" click on a node in an information set has the effect to apply to ALL nodes in that information set (i.e. all subtrees will be removed, and the information set itself dissolved). I am not sure I like this behavior - I think it would be better to just take the node out of this information set, but this is a separate issue.