Improve fund burning and abstract costs

[Tomasvrba]

Currently the burnSignal contract burns funds as follows:

Whenever funds are received on one of the VoteOptions contracts via the receive() function, two things happen:

• An event is emitted with the value of the deposit, address of the sender, name of the option and name of the parent proposal
• The contract attempts to burn the funds by forwarding them to the 0x0 address and emits a success BurnedDeposit event when successful (see https://github.com/Tomasvrba/burnSignalContracts/blob/burn-address/burnSignal.sol#L25)

There are two issues/areas for improvement with this approach:

• This burn transfer happens on every deposit, adding an additional transaction to the network for each vote
• The additional gas cost is incurred by the voter (roughly doubled since we are executing an extra transaction)

What should happen:

• For efficiency, batch burn transactions together (e.g. when VoteOption contract balance surpasses a certain threshold)
• Abstract the additional gas cost so it's not paid by the voter (e.g. Have the issuer of the proposal fund both the yes/no options with some funds to execute these transactions, these funds could be returned to the issuer after the deadline when the contract selfdestructs)