OpName is only for debug information, so we must be very careful that
we do not reuse the same name for different variables.
This was previously done for local variables, but this commit extends
this to global variables as well.
This is supported as compiler extensions, but we can be standards
compliant here, so use the classic workaround of having a single entry
array at the end of the structs instead.
Reformats the entire codebase. Better to do it now than later.
Adds .clang-format and a convenience script format_all.sh which formats
everything automatically.
