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)

apps/references.d.ts

@@ -1,5 +1,4 @@
 /// <reference path="../tns-platform-declarations/android.d.ts" />
 /// <reference path="../tns-platform-declarations/ios.d.ts" />
 
-/// <reference path="../tns-core-modules/tns-core-modules.d.ts" />
 /// <reference path="../tns-core-modules/ui/styling/css-selector-parser.d.ts" />

apps/tsconfig.json

@@ -4,4 +4,4 @@
         "node_modules",
         "platforms"
     ]
-}
+}