Else not implemented in conditional transitions

[arscan]

You should be able to create an else 'condition' as the last transition, and move up/move down should be disabled for that. This applies complex transitions as well.

Implement at the same time as #161

[arscan]

Fixed in #187

On the final condition in conditional and complex transitions, you can remove the condition (button just shows up next to 'Else If:' right now). If no condition exists, you can add it (button shows up next to Else). A glaring red 'Add Condition' shows up if you have figured out a way to have a condition that isn't last not have a conditional. This can happen if you add a condition to the end of the list, after an 'else', or if you move around conditions. I didn't proactively try to fix these cases on behalf of the user, as that might result in unexpected conditions.