Allow custom implementations of LogMachine with xsbug_log

[cmidgley]

This PR is a proposal to add a tiny bit of extensibility to xsbug_log by allowing the LogMachine class to be overridden by an external module. Changes include:

• Pulled LogMachine out to it's own file xsbug-logmachine
• Added check if the XSBUG_LOGMACHINE environment variable is set and if so load that as the module for LogMachine (else defaults to the original version)
• Bit of documentation in the associated xsbug readme

I am requesting this change for a couple of reasons:

1) Support for colorization using the \, \, ... tags

I'm glad to provide this if interested, either as an update to the default LogMachine or as an optional one such as xsbug-colorlogmachine.js that can be selected with XSBUG_LOGMACHINE 2) I have a custom test runner, similar in concept to what xsbug does but unique to fit my needs, and I'm using xsbug-log to manage the logging and tracking of test executions.

[phoddie]

It is great that you are using the xsbug API for your test runner. I always thought that API would be useful for automation.

It feels a little strange to me to build an extension mechanism into xsbug-log. The implementation is so simple that you could just replace xsbug-log.js and use the same supporting modules. But, I understand that the extension mechanism helps to avoid some code duplication and simplifies integration with mcconfig and mcrun.

We'll get this merged.

Support for colorization using the , , ... tags I'm glad to provide this if interested, either as an update to the default LogMachine or as an optional one such as xsbug-colorlogmachine.js that can be selected with XSBUG_LOGMACHINE

This would be welcome. In the interest of simplicity, It seems fine to just update the default rather than providing an alternate.

[mkellner]

This has been merged and will be available in the next drop.