v3.0

[jonkadelic]

Tracking issue for version 3.0 of the update utility. The primary goals of v3.0 are:

• Interface with the new download API at https://downloads.betterthanadventure.net

• Allow the user to switch between different release channels - e.g. prerelease and nightly, not just release

• Allow the user to switch between different historical versions of BTA!
  To allow this, v3.0 will add a user interface to the project, rather than running in MultiMC's stdout capture. This interface is intended to have two modes: a "simple" mode that provides a one-click solution for downloading and updating the latest release version of the managed instance, and an "advanced" mode that allows the user to select a specific release channel and version.

• Create initial project

• Write code to pull info from the new download API

• Write code to manage the managed instance

• Write code to download and install a specific version to the managed instance

• Implement "Simple Mode" frontend

• Implement "Advanced Mode" frontend

• Add configuration files for legacy BTA! versions to download server

• Set up Jenkins project to generate releases of the updater