R# 2020 support

[mareklinka]

[BigHoss]

Any progress on that?

[stianeklund]

Out of curiosity I upgraded everything to .net48 and C# 8.0 and based on the project warnings etc:

From what I can tell parts of the plugin itself needs to be rewritten, ICache no longer exposes the same methods:

• Components\PatternManagercache
• Components\RegisteredTypeCollector
• Highlighting\ContainerGutterMark
• Highlighting\RegisteredByContainerHighlighting

• changes to the tests (probably a lot).