[build] Add csharp script to build the list of referenced source file in the csproj

This is to be used to generate the corresponding list in Makefile.am mainly to have a correct make dist target
[build] Add csfiles to the Makefile
[build] Add sln and csproj to dist target since they are now needed to be able to build.
[build] Add missing csfiles and csproj to tests Makefile.am
[build] Bump version number to 0.8.0