Log: New logging system.

Right now, all I've done is move the logging function from utils to its own
file. I've also refactored it and created some classes.

Next step would be to somehow get rid of the trace setting. The Remote class
should have nothing to do with logging settings. Perhaps we can keep the setting
for backwards compatibility only, but the main way to turn logging on/off or
filter logging messages should be through the Log class.