Add aria labels for oscar buttons

[fix] Preserve bangs in corrections

Fix out of range error in tracker remover plugin

Initialize support for offline engines

Config for instance name and autocomplete

Signed-off-by: mathieu.brunot <mathieu.brunot@monogramm.io>

Signed-off-by: mathieu.brunot <mathieu.brunot@monogramm.io>

No inline script for oscar and simple theme

Add image format and source information to display - needs changes to engines to actually display something. 

Displays result.source (website from which the image was taken) and result.img_format (image type and size).

Result is styled with result-format and result-source classes. See PR #1566 for an example of an engine which has the necessary changes.

Strip <span class="highlight">...</span> in the oscar image template.

This PR fixes the result count from bing which was throwing an (hidden) error and add a validation to avoid reading more results than avalaible.

For example :
If there is 100 results from some search and we try to get results from 120 to 130, Bing will send back the results from 0 to 10 and no error. If we compare results count with the first parameter of the request we can avoid this "invalid" results.

Engine fixes

before this commit, sometimes there are no results
use a generic user-agent instead of one with the OS "Windows NT 6.3; WOW64"