MCInstance Loader

Here is a small update before 3.0 to fix compatibility issues with custom main menus from mods.

Feature changes and fixes

• Fixed the mod not working with certain mods loaded
• Rewrote the main menu GUI detection code to be cleaner and more stable
• Removed the gui class path config (since it's no longer needed)

Technical changes

• Refactored some code internally to prepare for 3.0
• Bumped the version number to 2.6
• Updated the Zip4J library to 2.11.5