Update Workflow Improvements

Update workflow

• When update fails, prompt user to remove the build dir and retry the update.

Improve update count tracking

• Reset count to "?" when update fails or source dir is removed.
• Don't set count to 0 until after update succeeds.

What's Changed

• V2.0.0 Terminal Callbacks by @rootiest in #9
• V2.1.0 Update Workflow Improvements by @rootiest in #10

Full Changelog: v2.0.0...v2.1.0