Render themes: Android scoped storage, zip render theme, custom resource providers (#804)

vtm-themes/src/org/oscim/theme/VtmThemes.java

@@ -4,6 +4,7 @@
  * Copyright 2016-2021 devemux86
  * Copyright 2017 nebular
  * Copyright 2017 Andrey Novikov
+ * Copyright 2021 eddiemuc
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -59,6 +60,11 @@ public enum VtmThemes implements ThemeFile {
         return AssetAdapter.readFileAsStream(mPath);
     }
 
+    @Override
+    public XmlThemeResourceProvider getResourceProvider() {
+        return null;
+    }
+
     @Override
     public boolean isMapsforgeTheme() {
         return false;
@@ -71,4 +77,8 @@ public enum VtmThemes implements ThemeFile {
     @Override
     public void setMenuCallback(XmlRenderThemeMenuCallback menuCallback) {
     }
+
+    @Override
+    public void setResourceProvider(XmlThemeResourceProvider resourceProvider) {
+    }
 }