Move to a logging framework

[e3ndr]

Also make verbosity a log level instead of a boolean.

This allows us to silence all output from Twirk (Our console window currently looks like this)

[Gikkman]

Hi!

Sorry for the slow response! I hadn't seen this PR for some reason. I'll go ahead and test it out soon and get back to you.

Thank you for your effort!

[Gikkman]

Hi again!

I tested the code you suggested, and it works just as it should 👍 However, I received a message from some users of the library who mentioned backwards compatibility. Not everyone uses JUL, and some redirect System.out.println to their own custom methods for handling.

So instead, I used a lot of what you've done here and implemented a solution where you can provide your onw log methods to the TwirkBuilder, and those will then be called whenever a log message of a certain severity occurs. This is the most backwards compatible I can come up with, while still giving you and everyone using a log framework the ability to set your own logging methods.

You can see the implementation I went for in the 0.6.3 branch

Thank you for your effort!