Merge branch 'moar-zoom' into 'master'

Add more zoom levels

Closes #753

See merge request !1037

js/config.js

@@ -84,7 +84,7 @@ export const SEARCH_FILTER_MAX_TERMS = 10
 export const IMAGE_QUALITY = 1.5
 
 // Interactive image zoom factor in percent
-export const ZOOM_FACTORS = [100, 133, 166, 200, 250, 350]
+export const ZOOM_FACTORS = [100, 133, 166, 200, 250, 350, 400, 500]
 
 // Image navigation transitions delay for the zoom and the automatic centering (ms)
 export const IMAGE_TRANSITIONS = 300