No more ambient modules for tns-core-modules/* subpackages.

- Use path mappings in tsconfig.json to resolve module typings
- Only use ambient mobules for global API's
- Move single-file modules to a subdir with the same name so that
we can provide a hand-written typing next to it (via package.json)
- Delete all mentions of tns-core-modules.d.ts
- Delete reference d.ts assembly build steps. Not needed anymore.
- HACK! Use a <reference> for global typings in application.d.ts
to avoid publishing a separate @types/tns-core-modules package.
- Rename declarations.d.ts to tns-core-modules.d.ts to preserve
JS project mappings in references.d.ts (the only place we use those)

tns-core-modules/timer/timer.d.ts

@@ -1,30 +1,28 @@
 /**
  * Allows you to create, start, stop and react to timers.
  */
-declare module "timer" {
-    /**
-     * Calls a function after a specified delay.
-     * @param callback The function to be called.
-     * @param milliseconds The time to wait before the function is called. Defaults to 0.
-     */
-    export function setTimeout(callback: Function, milliseconds?: number): number;
+/**
+ * Calls a function after a specified delay.
+ * @param callback The function to be called.
+ * @param milliseconds The time to wait before the function is called. Defaults to 0.
+ */
+export function setTimeout(callback: Function, milliseconds?: number): number;
 
-    /**
-     * Clears the delay set by a call to the setTimeout function.
-     * @param id The identifier returned by the previously called setTimeout() method.
-     */
-    export function clearTimeout(id: number): void;
+/**
+ * Clears the delay set by a call to the setTimeout function.
+ * @param id The identifier returned by the previously called setTimeout() method.
+ */
+export function clearTimeout(id: number): void;
 
-    /**
-     * Calls a function repeatedly with a delay between each call.
-     * @param callback The function to be called.
-     * @param milliseconds The delay between each function call.
-     */
-    export function setInterval(callback: Function, milliseconds?: number): number;
+/**
+ * Calls a function repeatedly with a delay between each call.
+ * @param callback The function to be called.
+ * @param milliseconds The delay between each function call.
+ */
+export function setInterval(callback: Function, milliseconds?: number): number;
 
-    /**
-     * Clears repeated function which was set up by calling setInterval().
-     * @param id The identifier returned by the setInterval() method.
-     */
-    export function clearInterval(id: number): void;
-}
+/**
+ * Clears repeated function which was set up by calling setInterval().
+ * @param id The identifier returned by the setInterval() method.
+ */
+export function clearInterval(id: number): void;