Changes

Beginning of Directory.Build.props settings

Can create that file in the root with:

```
<Project>
  <PropertyGroup>
    <KspDir>/Users/lamont/ksp/plc_1.12.3</KspDir>
  </PropertyGroup>
</Project>
```

And it'll get passed into copy_build.sh

Or KSPDIR will override that setting

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>
 (commit: fab2471)