Add a variable with all the icons of the theme

Add for the template a list of available icons in the current theme.
Use the new way of finding an icon
Use the new way of finding the favicon
Use the new way of finding the favicon
Use the new way of finding the favicon
Use the new way of finding the favicon
Load the list of icons only once
Final commit on favicons
Definitely remove engine array
Change every themes to accomodate that change
Tweak of video template of oscar to add link on video thumbnail
Merge branch 'Detect-favicons' of https://github.com/Cqoicebordel/searx into Cqoicebordel-Detect-favicons

Conflicts:
	searx/templates/courgette/result_templates/default.html
	searx/templates/courgette/result_templates/map.html
	searx/templates/courgette/result_templates/videos.html
	searx/templates/default/result_templates/default.html
	searx/templates/default/result_templates/map.html
	searx/templates/default/result_templates/videos.html
	searx/webapp.py
Merge branch 'Cqoicebordel-Detect-favicons'
[enh] subtitleseeker: better language handling