Add a `.makefile` for immediate make targets

We can add various development activities to this alternate Makefile.

If you do this first:
```
ln {.,GNU}makefile
```

then you can use the new targets and the old ones without specifying the
`.makefile` in make commands and without worrying about bootstrap.

ie Before this, to use Makefile targets, you needed to run `./bootstrap`
and `./configure` first. This file will proxy all common Makefile
targets, first making sure that the Makefile exists.