Add Log util class

[tjsr]

First of two pull requests relating to this.

This PR adds a base logger which I plan on adding to and improving over the coming days - but it puts it in place for future use.

This allows moving away from calling the generic log function which are in the Util module, and adding new listeners and handlers to dual-output log events to stdout, a log file, and a debug output window. It will also allow logging things like timing device/decoder events from individual decoder types or individual decoder to their own individual log, and filtering logs by events.

This will also be used to help track down issues with the application exiting by trapping uncaught exceptions to std.excepthook.

[tjsr]

I've now re-written a fair bit of this so it relies less on handlers in the code, and defines them in a config file instead.

[tjsr]

Don't approve/merge this for now. I'm going to drastically improve it to have most of it configured from a config file.