Improved Unknown Assembly Experience/Messaging

[Mike-E-angelo]

Addresses #558

[AppVeyorBot]

✅ Build ExtendedXmlSerializer 3.7.5.4-wordbagt completed (commit 05b019a637 by @Mike-E-angelo)

Install it by running the following command in Package Manager Console:

Install-Package ExtendedXmlSerializer -Version 3.7.5.4-wordbagt -Source https://ci.appveyor.com/nuget/extendedxmlserializer-preview

Problems with the above command? You may be running into this known issue here:
NuGet/Home#7189

[AppVeyorBot]

✅ Build ExtendedXmlSerializer 3.7.5.4-gqnhtakj completed (commit 461885c176 by @Mike-E-angelo)

Install it by running the following command in Package Manager Console:

Install-Package ExtendedXmlSerializer -Version 3.7.5.4-gqnhtakj -Source https://ci.appveyor.com/nuget/extendedxmlserializer-preview

Problems with the above command? You may be running into this known issue here:
NuGet/Home#7189

[AppVeyorBot]

✅ Build ExtendedXmlSerializer 3.7.5.4-kclscxur completed (commit 95b6147565 by @Mike-E-angelo)

Install it by running the following command in Package Manager Console:

Install-Package ExtendedXmlSerializer -Version 3.7.5.4-kclscxur -Source https://ci.appveyor.com/nuget/extendedxmlserializer-preview

Problems with the above command? You may be running into this known issue here:
NuGet/Home#7189