Resolve issue with Request ContentLength casing

Issue #389

Port to C# 8

Upgraded codebase to C# 8.0. We are not using .NET Standard 2.1 yet.

Also, fixed issue #351

Add Strong-name to EmbedIO Assembly

Add Strong-name to EmbedIO Assembly (Issue #363)

Update to SWAN 2.2.0

Important update to SWAN JSON Serializer/Deserializer v2.2.0

Fix Response Content Length issue

• Issue #355
• Update to SWAN 2.1.0

Fixed issue with FileSystemProvider paths

Fixed issue #352

Resolve issue with RouteMatcher cache

Issue #347
PR #348

Changes to logger

Change some Info level logs to Debug

Major version 3.0.0

Breaking changes

• New Assembly name EmbedIO.dll.
• New Assembly with unit Testing support classes and TestWebServer: EmbedIO.Testing.dll.
• Remove Routing Strategy: everything is using Regex resolution of routes.
• Remove return bool for WebModule, a new pipeline is available
• Remove return bool or return Task for WebAPI Methods, you can return anything and the serializer will take control.

We will update the following wiki page for upgrade notes:

https://github.com/unosquare/embedio/wiki/Upgrade-from-v2

Last version before v3.0

This version hides some internal classes and methods like WebSocket and mark with Obsolete attribute classes, methods and properties that will be dropped or replaced in the new major version.