Style error messages

[jeroen]

The error messages in the player could use a little styling love. Some suggestions:

• Make the padding of the text in the box a lot bigger, e.g. 20px.
• Don't have the box extend through the entire width of the display, but add 20px margin left/right.
• Add a headline (e.g. in <font size="+2"><b>) saying Error:.
• Make the textfield multiline and autosize:center. That way, large error messages will also fit. Consequently, the black background should get drawn or resized after the error text is set, otherwise the text may run outside it (which it the case today).

[jeroen]

Attached is an example of how it would look.

[pablo]

6.0 will address general layout and UI enhancements