Add CSS to style disabled buttons.
Disable buttons when they would do weird stuff.
Make up and down arrow keys change the number.

Also generalized the "only numbers allowed in that text field"
Show vote buttons, when stopping. Fixes #88
Preload prediction symmettical. Fixes #85
Do not pause the current Frame on 'play' pressed.
Merge pull request #87 from MaPePeR/some-fixes

Fixes #84, #85, #88 and adds up and down keybindings to the frame-input-fields.