Jaysvcutil enhancements

[raveclassic]

Thanks for such a great utility first!

Unfortunately I cannot find the source here, so there's no way to open a PR for impromevents. Here are some of them:

• $data.Qeuryable is missing some methods. One of them is withInlineCount. Also seems like length and count duplicate each other.
• $data is a module but could be a namespace to allow TS namespace merging so that one could extend base EntitySet/Queryable classes. For example it is possible to fix Queryable with:

  
  import * as base from './context';

declare module './context' { namespace $data { interface Queryable<T extends base.$data.Entity | base.Edm.Primitive> { withInlineCount(this: Queryable): this; withCount(this: Queryable): this; } } }

But it is only possible when manually replacing `module` by `namespace` in generated `./context.d.ts` file.
- It would be extremely useful to allow custom `.d.ts` file templates for generation. Currenly its `JayData.src` in `jaydata-dynamic-metadata/src/dts.ts`

[ogrim]

Is this the source you are looking for? https://github.com/jaystack/jaysvcutil