ci: remove --output from dotnet pack, put output directory to Directory.Build.props

chore: make README.md be copied to root of package

chore: include readme and license in package

chore: move repository url and license to Directory.Build.props

chore: add async analyzer and meet its standards

Merge pull request #12 from Rutherther/packets

Implement custom packet serializer

chore: add stylecop, ensure stylecop rules are met