[core, ios, osx, android, glfw] Flipped origin of Map::latLngForPixel(), Map::pixelForLatLng()

Map and Transform methods assume an origin at the top-left corner of the view, like iOS, Android, and GLFW but unlike OS X. Transform is responsible for flipping coordinates between the top-left origin of Map and the bottom-left origin of TransformState.

Fixes #3574.

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/views/MapView.java

@@ -2264,9 +2264,6 @@ public final class MapView extends FrameLayout {
         float x = point.x;
         float y = point.y;
 
-        // flip y direction vertically to match core GL
-        y = getHeight() - y;
-
         return mNativeMapView.latLngForPixel(new PointF(x / mScreenDensity, y / mScreenDensity));
     }
 
@@ -2289,9 +2286,6 @@ public final class MapView extends FrameLayout {
         float x = point.x * mScreenDensity;
         float y = point.y * mScreenDensity;
 
-        // flip y direction vertically to match core GL
-        y = getHeight() - y;
-
         return new PointF(x, y);
     }