[wikiart] add extractors (#179)

for
- artists:          https://www.wikiart.org/en/thomas-cole
- artist-listings:  https://www.wikiart.org/en/artists-by-century/12
- artwork-listings: https://www.wikiart.org/en/paintings-by-media/grisaille

test/test_results.py

@@ -25,8 +25,9 @@ TRAVIS_SKIP = {
 
 # temporary issues, etc.
 BROKEN = {
+    "komikcast",
+    "mangahere",
     "mangapark",
-    "nyafuu",
 }