Added type declarations

types/themes.d.ts

@@ -0,0 +1,38 @@
+import Rendition from "./rendition";
+import Contents from "./contents";
+
+export default class Themes {
+  constructor(rendition: Rendition);
+
+   register( themeObject: object ): void;
+
+   register( theme: string, url: string ): void;
+
+   register( theme: string, themeObject: object ): void;
+
+   default( theme: object | string ): void;
+
+   registerThemes( themes: object ): void;
+
+   registerUrl( name: string, input: string ): void;
+
+   registerRules( name: string, rules: object ): void;
+
+   select( name: string ): void;
+
+   update( name: string ): void;
+
+   inject( content: Contents ): void;
+
+   add( name: string, contents: Contents ): void;
+
+   override(name: string, value: string, priority: boolean): void;
+
+   overrides(contents: Contents): void;
+
+   fontSize(size: string): void;
+
+   font(f: string): void;
+
+   destroy(): void;
+}