Dockerfile : bug fixes. 
Perhaps "COPY requirements.txt ./requirements.txt" is unnecessary but it doesn't hurt (instead of "COPY requirements.txt .")

Simpson screenshot search engine

[fix] typo

[enh] WolframAlpha no API engine (and tests for both)

 - searx/settings.yml is the right name in second sed line
 - COPY requirements.txt . does not work: "Not a directory"

Conflicts:
	searx/tests/test_engines.py