Use default index + user-lang index in autocomplete

[Joxit]

The lang boos is 2x higher than default index to promote lang matching first.
Default lang is en.

related: #1296

[Joxit]

I ran an acceptance test on our production server

-	v3.65.0	multi-lang-index
Pass	535	533
Improvements	18	18
Fail	91	91
Placeholders	0	0
Regressions	65	67
Test success rate	90.59%	90.3%

Changes:

--- master	2019-05-20 16:16:10.936988085 +0200
+++ branch	2019-05-20 16:25:08.797239420 +0200
@@ -300,9 +300,11 @@
  ✔ [1-3] "{"text":"brookl"}"
  ✔ [1-4] "{"text":"brookly"}"
  ✔ [1-5] "{"text":"brooklyn"}"
-  ✘ regression [2] "{"text":"new york"}": score 1 out of 2
+  ✘ regression [2] "{"text":"new york"}": score 0 out of 1
  diff:
-    priorityThresh is 5 but found at position 7
+    label
+      expected: New York, NY, USA
+      actual:   New York County, NY, USA
  ✘ [3] "{"text":"london"}": score 9 out of 10
  diff:
    priorityThresh is 5 but found at position 7
@@ -366,21 +368,39 @@
    label
      expected: Union Square, San Francisco County, CA, USA
      actual:   Union Square, Union City, CA, USA
-  ✔ [4] "{"focus.point.lat":52.507054,"focus.point.lon":13.321714,"text":"hard rock cafe"}"
-  ✔ [5] "{"focus.point.lat":40.744243,"focus.point.lon":-73.990342,"text":"hard rock cafe"}"
+  ✘ regression [4] "{"focus.point.lat":52.507054,"focus.point.lon":13.321714,"text":"hard rock cafe"}": score 0 out of 1
+  diff:
+    label
+      expected: Hard Rock Cafe Berlin, Berlin, Germany
+      actual:   Hard Rock, Myanmar
+  ✘ regression [5] "{"focus.point.lat":40.744243,"focus.point.lon":-73.990342,"text":"hard rock cafe"}": score 0 out of 1
+  diff:
+    label
+      expected: Hard Rock Cafe, Manhattan, New York, NY, USA
+      actual:   Hard Rock, Myanmar
  ✘ [24] "{"focus.point.lat":37.743618,"focus.point.lon":-122.426117,"text":"zoo"}": score 2 out of 3
  diff:
    priorityThresh is 1 but found at position 3
  ✔ [25] "{"focus.point.lat":40.744131,"focus.point.lon":-73.990424,"text":"1 madison ave"}"
  ✔ [26] "{"focus.point.lat":40.744131,"focus.point.lon":-73.990424,"text":"w 26th st"}"
-  ✘ [27] "{"focus.point.lat":41.05343,"focus.point.lon":-73.53873,"text":"New York"}": score 3 out of 5
+  ✘ [27] "{"focus.point.lat":41.05343,"focus.point.lon":-73.53873,"text":"New York"}": score 1 out of 4
  diff:
-    New York,New York is not close enough, distance=3463 m
-    priorityThresh is 1 but found at position 6
-  ✘ [28] "{"focus.point.lat":41.05343,"focus.point.lon":-73.53873,"text":"New York, NY"}": score 3 out of 5
+    name
+      expected: New York
+      actual:   Deutsche Schule New York
+    layer
+      expected: locality
+      actual:   venue
+    Deutsche Schule New York,White Plains is not close enough, distance=42435 m
+  ✘ [28] "{"focus.point.lat":41.05343,"focus.point.lon":-73.53873,"text":"New York, NY"}": score 1 out of 4
  diff:
-    New York,New York is not close enough, distance=3463 m
-    priorityThresh is 1 but found at position 10
+    name
+      expected: New York
+      actual:   New York State Thruway
+    layer
+      expected: locality
+      actual:   street
+    New York State Thruway,South Nyack is not close enough, distance=47232 m
  ✔ [29] "{"focus.point.lat":40.744131,"focus.point.lon":-73.990424,"text":"San Francisco"}"

autocomplete jitter

I need to know why Hard Rock Cafe is not passing with this feature.

[Joxit]

Moved to #1300 (git fail 😅 )