* update from ionicons-npm to ionicons ver.5
* drop the webfont built by grunt for icons
* built icons.html template for inlining icons with jinja2 into html
* update icon to use mostly the outline version
* add icons to categories and do not display them on mobile to save space
* remove all legacy ion icon font files from simple theme
* icons.html is added in this commit since make statc.build.restore requires git to know the file already
* cleanup error-dialog
- npm package update
- apply #1226
- implement vim help dialog
- display cookies and search URL with preferences
- allow to enable / disable Open Access DOI rewrite
- add a clear text button on the left of the search button
- implement #1011 : the HTML title page is not set when using POST
- remove searx/static/themes/simple/img/loader.gif
- use full width when only there are only images as result