Make it possible to include log record.file() / record.line()

[brandonros]

https://stackoverflow.com/questions/61810740/log-source-file-and-line-numbers I could be wrong but I think at the moment such functionality is impossible with this library?

[fvacek]

I also like to have this feature, it's hard to find origin of log message in source code, what makes bug hunting more difficult. My implementation is here. e0abd42