use a sparql request on wikidata to get the list of currencies.
currencies.json contains the translation for all supported searx languages.
Supersede #993
* searx understand "!ddg !g time" as : send "!g time" to DDG
* !g a DDG bang for Google: DDG return a HTTP redirect to Google
This commit adds a the allows_redirect param not to follow HTTP redirect.
The DDG engine returns a empty result as before without HTTP redirect.
the query "time" is convinient because most of the search engine will return some results,
but some engines in the general category will return documentation about the HTML tags <time> or <input type="time">
from_bang is True when the user query contains a bang.
In this case the category is also set to 'none'.
from_bang only usage was in searx.webadapter.parse_specific :
if from_bang is True, then the EngineRef category is ignored and force to 'none'.
This commit also removes the searx.webadapter.parse_sepecific function.
see searx.search.processors.abstract.EngineProcessor
First the method searx call the get_params method.
If the return value is not None, then the searx call the method search.
