Don't ignore all svg images when building.

Svg files that are not inlined must be contained by the built.
Change text, images on index page

plus some minor adjustments.
new header
Refactor header
make info-boxes wider
Youtube player fix wrong origin problem.

When using youtube's iframe player api the videos has to be
loaded via https.
Fix typo in ga tracking of teaser video link.
Better spacing for main pages.
fix spacing for sharing-links
Keep footer at bottom on short pages.