Webclient fix: revealing search results (#315).

Revealing topics from a search result works again.
Thanks, Malte, for reporting!

When hovered the Search Result field is not highlighted by a blue frame anymore.

Its more difficult to corrupt Topicmaps. Adding invalid associations (a player topic is missing) fail early. The topicmap remains usable. Client side errors like
    `Uncaught TypeError: Cannot read property 'x' of undefined`
should not occur anymore.
This applies to Topicmaps created from now.
If you have a corrupt topicmap (which does not render anymore) please tell me. I will send you repair instructions.

See #315.