Enforce .NET framework naming rules

The [official C# capitalization conventions](https://docs.microsoft.com/en-us/dotnet/standard/design-guidelines/capitalization-conventions) define how things should be named in C#. Note that these are officially guidelines, but they are followed by virtually everyone. As such, they are the _de facto_ standard and we should make any violation of the naming conventions an error. See:

- https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-naming-conventions?view=vs-2017
- https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-code-style-settings-reference?view=vs-2017