- Incorporated free text search thanks to sigmarsson (https://github.com/sigmarsson)
- Dropped support for portable-net45+win8 and netstandard1.1
- Addes support for net47, net5.0, netcoreapp3.1, and net4.7
- restructured library code into one project with multiple targets
- restructured test code into one project, dropped net40 test