Added dpm package spec file

[vincentparrett]

This file adds support for the https://github.com/DelphiPackageManager/DPM

To create packages, install dpm (see getting started link in the readme), then in you local repo folder

dpm pack NesLib.NesLib.dspec -o=c:\dpmfeed (or where ever you want your packages to go).

Ideally you would create a versions release here on github and attach the package files to the release - at least until we have a package server site up and running (in development).