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.
Preparation: Moved color code into one method

The method setupContext is now used to set up the drawing context for a
particular frame, setting its fill- and strokeStyle.
Implements #89.
Rearranged preload indicator legend and added entry

Text is still missing because I don't know the font (in fact, as I'm currently on a Linux machine, it's quite possible I don't even *have* the exact font).
Replace the legend png with an equivalent SVG file.

This closes #89.
Removes color declaration duplicity

ayop-preload.js now fetches the colors from preloadindicator_legend.svg.
Remove debug code

whoops
Fix formatting

A few indentations in index.html were still tabs
Merge pull request #93 from lucaswerkmeister/implement-89

Implement #89
Fix a small untracked bug

where the cursor would stay on the very last frame (again, a rogue '<' instead of '<=')
Fixes part of #95

the "overflow" is fixed, instead now the cursor "stays behind"...
Fix another part of #95

but now future frames get colored "unloaded" when mouse-overing them
Completely fixes #95.

I don't see any more bugs in the preload indicator mouseover...
Nicer syntax for parseInt("")-protection

As suggested by MaPePeR in ##95, protection against parseInt("") = NaN
is now done through appending "|| 0" to the expression instead of
prepending "0" to the string