Add launcher auto-update

[ViRb3]

Fixes #8.

[ViRb3]

After an initial investigation, it appears that the upstream updater is set up to download individual delta files between versions. This is a lot of effort, especially since the app is now signed and all files will always differ across versions, even if they were unchanged. A re-write of the updater is likely going to be necessary.

~~For now, I plan to fix #10 which will make manual updates a lot easier.~~ Fixed in build 5!

[ViRb3]

This is now partially possible via Homebrew. Check the updated installation guide for detailed info, but in short, you can now update with just one command:

brew upgrade --no-quarantine ManyMC

[david-tao-as01]

This is now partially possible via Homebrew. Check the updated installation guide for detailed info, but in short, you can now update with just one command:

brew upgrade --no-quarantine ManyMC

Is there a plan for MacPorts users?

[ViRb3]

Not from me, but feel free to submit a package to MacPorts.