[enh] simple theme: RTL support

* mirror all inline SVGs so that direction SVGs display correctly on RTL
* set the bold list element in info box to RTL so the colon gets displayed on the right side
* set correct .ltr function for the left border on the search button in #q
* move text to the right in autocomplete
* move search form in lign with result article on RTL
* add the correct padding for img thumbnails in categories like music on RTL
* apply RTL to result table for map results
* align text in tables part of /preferences on RTL
* move burger menu on index page to the left on RTL
* fix positioning of drop down arrow on select boxes on RTL
* align result URL on the right (written LTR)
* align vim hotkeys help on the left since it is not translated
* image detail:
  * labels (author, format, URL, etc...) are written on the right,
    values are on the left.
  * URL are written LTR and overflow on the right

searx/static/themes/simple/gruntfile.js

@@ -127,7 +127,7 @@ module.exports = function (grunt) {
         },
         files: [
           {
-            src: ['src/less/style.less'],
+            src: ['src/less/style-ltr.less'],
             dest: 'css/searxng.min.css',
             nonull: true,
             filter: file_exists,