DOC: News items and link to photos

some news items regarding meeting at the LAC and the
just finished C++11 transition. Additionally, link
to the images from our Excursion last August.
These imare are still kind of a preview (someone
should write a nice text).
improved robots.txt

- should not visit the binary contents of our DEB repository
- but doxygen is fine
- add a specific version for the trac (subdomain)
- exclude the expensive calls from the trac
- throttle down https://ahrefs.com/robot/