Make batch method generic, similiar to Promise.all

The goal of this commit is to improve the type definitions for the `batch` method so that it behaves more like `Promise.all`.

Currently, when `batch` resolves it always resolves to an array with type `any[]` which means we've lost all type information about the values sent in.

This commit aims to preserve the type information for arrays and tuples of length 2 through 10.

Now:

```ts
import Spex from './typescript/spex';

async function testTuples(s: Spex.ISpexBase) {
  const result = await s.batch(['1',Promise.resolve(2)]);
  const [a, b]: [string, number, boolean] = result;

  # IArrayExt duration value still works
  const duration: number = result.duration;

  // the above should behave same for tuples of length 2 through 10.
  // With more than 10 values, the result array items would all have
  // type string | number | boolean
}

async function testArbitraryLength(s: Spex.ISpexBase, toResolve: Promise<number | string>[]) {
  const result: Spex.IArrayExt<number | string> = await s.batch(toResolve);
  const duration: number = result.duration;
}
```

Hardcoding 9 type definitions for tuples of length 2 through 10 is not particularly elegant. I do not know if there is a better way, but this seems to follow the [typescript definitions of Promise.all](https://github.com/microsoft/TypeScript/blob/2428ade1a91248e847f3e1561e31a9426650efee/src/lib/es2015.promise.d.ts).

typescript/spex.d.ts

@@ -133,7 +133,16 @@ declare namespace spex {
     interface ISpexBase {
 
         // API: http://vitaly-t.github.io/spex/global.html#batch
-        batch(values: Array<any>, options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<IArrayExt<any>>;
+        batch<T>(values: (T | Promise<T>)[], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any}): Promise<IArrayExt<T>>;
+        batch<T1, T2>(values: [T1 | Promise<T1>, T2 | Promise<T2>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2] & IArrayExt<T1 | T2>>;
+        batch<T1, T2, T3>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3] & IArrayExt<T1 | T2 | T3>>;
+        batch<T1, T2, T3, T4>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4] & IArrayExt<T1 | T2 | T3 | T4>>;
+        batch<T1, T2, T3, T4, T5>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5] & IArrayExt<T1 | T2 | T3 | T4 | T5>>;
+        batch<T1, T2, T3, T4, T5, T6>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>, T6 | Promise<T6>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5, T6] & IArrayExt<T1 | T2 | T3 | T4 | T5 | T6>>;
+        batch<T1, T2, T3, T4, T5, T6, T7>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>, T6 | Promise<T6>, T7 | Promise<T7>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5, T6, T7] & IArrayExt<T1 | T2 | T3 | T4 | T5 | T6 | T7>>;
+        batch<T1, T2, T3, T4, T5, T6, T7, T8>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>, T6 | Promise<T6>, T7 | Promise<T7>, T8 | Promise<T8>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5, T6, T7, T8] & IArrayExt<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8>>;
+        batch<T1, T2, T3, T4, T5, T6, T7, T8, T9>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>, T6 | Promise<T6>, T7 | Promise<T7>, T8 | Promise<T8>, T9 | Promise<T9>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5, T6, T7, T8, T9] & IArrayExt<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9>>;
+        batch<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(values: [T1 | Promise<T1>, T2 | Promise<T2>, T3 | Promise<T3>, T4 | Promise<T4>, T5 | Promise<T5>, T6 | Promise<T6>, T7 | Promise<T7>, T8 | Promise<T8>, T9 | Promise<T9>, T10 | Promise<T10>], options?: { cb?: (index: number, success: boolean, result: any, delay: number) => any }): Promise<[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10] & IArrayExt<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>>;
 
         // API: http://vitaly-t.github.io/spex/global.html#page
         page(source: (index: number, data: any, delay: number) => any, options?: { dest?: (index: number, data: any, delay: number) => any, limit?: number }): Promise<IPageResult>;