Update Language Server Protocol NuGet package version 16.4.30

Use default language client settings if they exist

Fix exception on quitting IDE

Update language server protocol NuGet package

Fix failure to load language server addin

Fix some build warnings

Target .NET 4.7.2

Update package reference versions to match MonoDevelop 8.1

Implement workspace symbol provider in mock language server

Define package reference versions in one place

Initialize language clients in document controller extension

Fix didOpen message not being sent.

Support MonoDevelop 8.1

Support MonoDevelop 8.0

Update readme