Destroy and Start buttons in editor

[a-gerhard]

the backend has become much more powerful:

• allowing element start in created state
• allowing element destroy in started state
• allowing topology deletion with any elements in any states

the editor has some functionality that was to bridge this gap. the editor should lose this functionality and use that of the backend that has been created specifically for this purpose.

[a-gerhard]

The relevant code is in topology.js - @dswd there is a lot of complicated action stuff in there, please check if we can get rid of that (it's your code)