Add nice and tiny litte tool tips for all icons

[lumbric]

I'd suggest to have nice little tiny title texts for those buttons without text:

• what do the colours mean for the list of cocktails? (red/yellow/green)
• resume button
• abort button
• ...

Do you want to take this issue, @petres? (otherwise you can assign me)

[lumbric]

Minor other interface improvement: link to the serial interface

[petres]

green - rated and poured red - maybe rated and not poured yellow - who knows, maybe in queue?

colors are simple nice also without meaning!

tool tips are coming, link also!