Improve debugging with custom visualizers

On MSVC, there's Natvis, which is XML-based variable renderer: [https://docs.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2019](https://docs.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2019).

On GDB, there're Python scripts for rendering variables: [http://plohrmann.blogspot.com/2013/10/writing-debug-visualizers-for-gdb.html](http://plohrmann.blogspot.com/2013/10/writing-debug-visualizers-for-gdb.html).