Adds TypeScript definition for the package's supported public surface area.

Note: While this function takes and returns a string, the string is really JSON with a very specific and well defined structure.  A future PR will (hopefully) add the definitions for those JSON objects.  This PR is meant to be an agreable starting point for getting TypeScript definitions included.

Author: Micah Zoltu

index.d.ts

@@ -0,0 +1,5 @@
+declare module 'solc' {
+  export type ReadCallbackResult = { contents: string } | { error: string }
+  export type ReadCallback = (path: string) => ReadCallbackResult
+  export function compile(input: string, readCallback?: ReadCallback): string;
+}

package.json

@@ -3,6 +3,7 @@
   "version": "0.5.0",
   "description": "Solidity compiler",
   "main": "index.js",
+  "types": "index.d.ts",
   "bin": {
     "solcjs": "solcjs"
   },