Now uses a model and a list view instead of text
This lets mmc keep track of the contents regardless of whether the instance windows are open
This is currently missing a way to select and copy text from the log.
* The resulting instance window can be closed at any point.
* Main window is kept open and running instances are marked with a badge.
* Multiple instances can now run from the same MultiMC - it's even more **multi** now.
* MultiMC can be entirely closed, keeping Minecraft(s) running.
