Merge branch 'news/fix-course-announcement' into 'master'

See merge request [!223]

  [!223]: Noneinfrastructure/dune-website/merge_requests/223

Merge branch 'master' into 'master'

See merge request [!222]

  [!222]: Noneinfrastructure/dune-website/merge_requests/222

Merge branch 'news/pdelab-course-2019' into 'master'

See merge request [!221]

  [!221]: Noneinfrastructure/dune-website/merge_requests/221

Merge branch 'gallery/add-root-soil' into 'master'

See merge request [!220]

  [!220]: Noneinfrastructure/dune-website/merge_requests/220

Merge branch 'feature/new-news-layout' into 'master'

ref:infrastructure/dune-website So far on the main page, news entries are put
into separate lists according to the content key: 'corerelease', 'event',
'release', 'publication', 'application'.

One box contains all news entries tagged with 'corerelease'. Entries are shown
in full (e.g. new release and bug fix release).

In contrast to previously only the title of the other news items are shown on
the main page - with a link to the full text. There is a box for 'event' (e.g.
user meeting, school), for 'release' (release of other modules e.g.
dune-python, dune-functions), and for 'publications'.

All news entries are available when scrolling down (not only a few as was
previously the case).

Finally there is a further box showing news with the tag 'application'. These
should also contain a parameter 'image' pointing to an image which will be
shown next to a short text in an automatic switching gallery.

TODO:

-   \[ \] link news entries to anchor
-   \[x\] add overview pages per news-tag
-   \[x\] add "more" links to events and publications
-   \[ \] restructure publications
-   \[ \] perhaps add doi and preprint tag for publications to combine to a
    separate 'list of publications' page
-   \[ \] add button to enlarge to full-screen carousel

(fixes [#56], fixes [#28])

See merge request [!211]

  [#56]: gitlab.dune-project.org/NoneNone/issues/56
  [#28]: gitlab.dune-project.org/NoneNone/issues/28
  [!211]: gitlab.dune-project.org/infrastructure/dune-website/merge_requests/211


Closes #56 and #28

- content -> tag
- per tag news page
- add links from side-panel boxes to tags lists
- add tag cloud for news page

The current layout intends to completely hide the subtitle
by letting the main title take up the whole vertical space
of the header. However, at small screen width, the upper half
of the sub-title spuriously shows up.

Now it's no longer hidden by spacing but explicitly.

<!--more--> tag.

Merge branch 'feature/new-news-layout-2' into 'feature/new-news-layout'

ref:infrastructure/dune-website see discussion in [!211]

See merge request [!218]

  [!211]: gitlab.dune-project.org/NoneNone/merge_requests/211
  [!218]: gitlab.dune-project.org/infrastructure/dune-website/merge_requests/218

- make caption more readible

- add link to the releases page
- fix download link
- improve button layout

Merge branch 'fix-lowered-submenu-indicators' into 'master'

ref:infrastructure/dune-website Apparently, floating content in a
`white-space: nowrap` parent will end up on a line after any previous content
in the same parent in firefox 60, but not firefox 63. Fix this by putting the
floating content first; it occupies no space in its parent anyway, so any
other content should be unaffected.

Tested on firefox 60, 63, and chromium 70

Closes: [#58]

See merge request [!217]

  [#58]: gitlab.dune-project.org/NoneNone/issues/58
  [!217]: gitlab.dune-project.org/infrastructure/dune-website/merge_requests/217


Closes #58

Apparently, floating content in a `white-space: nowrap` parent will end up on
a line after any previous content in the same parent in firefox 60, but not
firefox 63.  Fix this by putting the floating content first; it occupies no
space in its parent anyway, so any other content should be unaffected.

Tested on firefox 60, 63, and chromium 70

With the old layout the ".wrapper .row{margin:0px;}" overwrites
the "margin:-15px" of bootstrap. However, in the modified layout
the .row is no longer contained in a .wrapper but in #main-content.

Browsers seem to expect a space between operators and numbers
in css calc() expresions. The firefox inspector shows an error
for calc(100% -2ex) while calc(100% - 2ex) is accepted and works
as expected.