Prevent vote delegation to oneself

[Elblinator]

Description:
A participant can delegate their vote to themselves

how to recreate:

1. activate delegations (settings > participants > activate vote delegation)
2. create new participant and delegate vote to themselves
3. start a vote
4. login as the participant and try to vote, a message is presented: Your voting right was delegated to another person.

wanted behaviour:
A user should not be able to delegate their vote to themselves.

[jsangmeister]

Sounds like a backend error - the backend should prevent such a delegation.