nanoFramework Metadata Processor v1.12.1

Initial commit

- Add readme and other docs.
- Add source code from nf-tools repo.
- Add Nerdbank.GitVersioning to project.
- Update MDP code to get version from executable.
- MDP is now made available as NuGet package.
- Add Azure pipelines yaml.
- Add nf-interpreter as sub-module.

Signed-off-by: José Simões <[email protected]>