v3.15.4212.0: Major upgrade

This is a stable production release.

Change Log

• upstream upgrade Builder to latest version.
• updated to netcore sdk 2.2
• bugfixes on csproj templating
• added net45 and net46 targets
• default to allow no doc for test projects
• fixed a bug with no output being produced with xunit
• fixed a bug with message resource (whitespace handling)
• fixed a bug with unicode char in assembly info file
• fixed a bug with autoversion feature not working reliably
• deprecated dependency on PSJapson for JsonPlus
• removed some unnecessary files for a smaller package size