Used @nodiscc suggestion in #1148 (slightly edited).
It provides a description of what Shaarli does, Markdown rendering demo, and a thumbnail link.
Fixes#1148
If a PHP is raised while executing plugin hook, Shaarli will display an error instead of rendering the error page (or just ending in fatal error for default hooks).
Also added phpErrorHandler which is handled differently that regular errorHandler by Slim.:
If the option is enabled, it will try to find a meta tag containing
the page description and keywords, just like we do for the page title.
It will either look for regular meta tag or OpenGraph ones.
The option is disabled by default.
Note that keywords meta tags is mostly not used.
In `configure` template, the variable associated with this setting
is `$retrieve_description`.
Fixes#1302
- add a default thumb size value (125x90px)
- improve private vertical bar visual, especially with thumbnails
- translations
- add a sync thumbs button in tool and empty picwall page
- fixes WT download mode in JSON config
* Added german language selection
* German language file created
* typo
* extra space removed and typo corrected
* lines 1314 through 1408 removed as suggested
When the key filter is clicked once, it only displays private link. When it is clicked on again, it becomes red and only public links are displayed. Another click and all links are displayed. The current visibility status is shown in the search banner
Fixes#1030
* translation system and unit tests
* Translations everywhere
Dont use translation merge
It is not available with PHP builtin gettext, so it would have lead to inconsistency.
