Improved alpha version, mainly performance and UX

Works as follows:

Bank sends hash
User sends value
Bank sends value + requests game evaluation

Same level of security, but a lot faster. Also added two options to make it even faster:

(1) Skip waiting for bank hash: Generally since the bank hash is submitted first, a subsequent user value will reach the contract at a later point in time. However in rare cases the opposite can happen. If you chose the skip waiting for bank hash option and this rare case happens, you will see an error. But you can just press "Spin" again and it picks up the game where it left.

(2) Pre-calculate and show game result: Don't wait for the smart contract to evaluate the game. We have the random values from bank and player, so we can calculate the end result in the front end. Note: The funds will update quite a bit later, because they are synchronized with the smart contract.