Fix the UI hanging for several seconds when opening the Controllers
window.
Move the scan for Bluetooth adapters onto a separate thread so the Host
thread doesn't have to wait for it.
Only automatically scan for adapters once, when opening the Controllers
window for the first time. Add a Refresh button to let the user refresh
the adapter list afterward.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
Joshua Vandaële