OSM OpenMapTiles style (#1420)

* OpenMapTiles style

* Rename style snippets from layer_name.json to defaultstyle.json

* Add README to icons dir.

* Add README to icons dir.

* Rename snippets to style.json

* Fix spritezero - move icons to svg subdir

* Move icons from style/icons/svg directly to style/icons

Co-authored-by: Tomas Pohanka <TomPohys@gmail.com>

style/icons/muslim.svg

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns="http://www.w3.org/2000/svg"
+   version="1.1"
+   width="14"
+   height="14"
+   viewBox="0 0 14 14">
+  <rect
+     width="14"
+     height="14"
+     x="0"
+     y="0"
+     id="canvas"
+     style="fill:none;stroke:none;visibility:hidden" />
+  <path
+     d="M 6,1 C 2.609585,1 0,3.6096 0,7 c 0,3.3904 2.609585,6 6,6 1.89566,0 3.873911,-0.6497 5,-2 -0.7358,0.479 -2.056597,1 -3,1 C 5.40733,12 3,9.5927 3,7 3,4.4073 5.40733,2 8,2 8.943403,2 10.2642,2.5211 11,3 9.873911,1.6498 7.89566,1 6,1 z M 10.5,4 9.5,6 7,6 9,7.5 8,10 10.5,8.5 13,10 12,7.5 14,6 11.5,6 10.5,4 z"
+     id="muslim" />
+</svg>