generating Nuget package
1) Build native and managed components by default
2) Add a workaround for package restoration to work on Mono
3) Add Nuget package support
4) Fix name casing for Linux
Populating repo with build infrastructure from the corefx project. Scripts are copied verbatim from the corefx repo as of commit 1ee4f60145a851adbacbb16e7b0c65bec3ec0d02.
Only minor changes were done to remove corefx-specific workarounds.
Also integrating the type system into the build.