Remove Map::start/stop

Both Android and iOS now use pause/resume. The map thread is
always running, and be able to receive messages. When paused,
it will just refuse to render.

test/api/repeated_render.cpp

@@ -22,9 +22,7 @@ TEST(API, RepeatedRender) {
 
     Log::setObserver(util::make_unique<FixtureLogObserver>());
 
-    Map map(view, fileSource);
-
-    map.start(MapMode::Still);
+    Map map(view, fileSource, MapMode::Still);
 
     {
         view.resize(128, 512, 1);
@@ -54,8 +52,6 @@ TEST(API, RepeatedRender) {
         util::write_file("test/fixtures/api/2.png", png);
     }
 
-    map.stop();
-
     auto observer = Log::removeObserver();
     auto flo = dynamic_cast<FixtureLogObserver*>(observer.get());
     auto unchecked = flo->unchecked();