Buttons for "Accept Realtime Battle" should be mutually exclusive

[dmcomm]

On the guest side, when we can start we can't retry, and vice versa.

[dmcomm]

Currently the start button isn't coming back when I put a new invite code.

[dmcomm]

Also the start button isn't disabled until after the status message fades.

[mechawrench]

These should be addressed if you can try again (on qa):

• Start button fixed to allow new invite codes, will reactivate button when the code changes
• Start button should be disabled shortly after pressing start (guest) now

[dmcomm]

Great! One more: On the guest side, if we try to reuse an invite code with a different WiFiCom Device, that should report an error, or maybe disable both buttons to be consistent.

Both fields same as before is a retry, invite code changed is a start, same invite code different device is not allowed.

Might have been simpler to program with just one button on the guest side, but probably more intuitive for the user having two.

[dmcomm]

I proposed on Discord:

• move device selection above invite code
• changing device selection clears invite code

(There still needs to be an error message if user submits the same invite code again.)

[dmcomm]

See #12