#982 Include news teasers on ESCET website home page

• Best to review per commit.
• End-user visible changes:
  • The ESCET home page now shows news teasers, with links to the news page.
  • Some spacing tweaks on the ESCET home page. This makes it slightly denser, so that the links to CIF, Chi and ToolDef remain visible without scrolling. I don't want to make it too dense, but these small tweaks are OK, I think.
• Other changes:
  • News items now only support a single tag. Previously, the news page supported multiple tags. But, we don't use it. And it doesn't fit very well with the compact news teasers on the home page.
  • Use more interesting dummy news items for debugging.
  • eclipse-escet.js: consistently use single quotes for strings, not double quotes.
• Notes:
  • We could make news teasers appear also on some other pages, but let's start with the ESCET home page.

Addresses #982