Previously plugins could declare js_dependencies and css_dependencies
which in theory would then be embedded in the page by themes.
Practically this does not make sense when you have multiple themes
since the JS & CSS needs to be written with a specific theme in mind
in order to support it.
Which is also why js_dependencies and css_dependencies was actually only
used by the Oscar theme and ignored by the Simple theme because the
Simple theme doesn't bundle jQuery and has a slightly different page
markup.
This commit removes this broken feature and also moves the *.js files in
searx/static/plugins/js/ to searx/static/themes/oscar/src/js/plugins
(where they actually belong).
The oscar-specific CSS is now simply injected via the oscar-specific JS.
Fixes#769.
Before this commit, in the documentation, the jinja context is 'webapp' and contains
the global variable in the searx.webapp module.
This commit changes this to include only the mandatory variables to build the
documentation.
