Logging (Core errors are ignored)

[LiHRaM]

Currently errors emitted by the error! macro from core is ignored in xi-win.
According to the log package, binaries using libraries which use macros from the log package need to have a logger which can receive the logs. The silent errors then make sense, as Core is used as a library by xi-win, which at the present uses no logger itself.

The fix seems to be initializing a logger early in the program.

I suggest just using something simple, like env_logger to receive the logs from core until a more complicated solution is needed.

Conveniently, we could also use this logger for tracing of commands, etc.

[dsp]

A few additional notes on logging:

1. I think on Windows the default is to always log to a file unless user specifies to log to stdout.
2. We should provide a "log" window to inspect the logs. This will help a great deal when debugging and will allow us to users eventually create a to a github issue with attached logs directly from Xi.