Add Homebrew formula for easy install

[kmturley]

You have a .zip release we can download at:
https://github.com/teragonaudio/MrsWatson/releases/download/0.9.8/MrsWatson-0.9.8.zip

We can access individual binaries at:
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Linux/mrswatson
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Windows/mrswatson.exe
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Linux/mrswatson
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Linux/mrswatson64
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Windows/mrswatson64.exe
https://raw.githubusercontent.com/teragonaudio/MrsWatson/0.9.8/bin/Windows/mrswatson.exe

But these require downloading the right binary and moving it to an easy-to-use location.

Homebrew allows easy installation of command line tools, such as:
brew install cmake

It's possible to submit new packages, and MrsWatson could easily be added using the guide at:
https://docs.brew.sh/Formula-Cookbook

Then users could simple install binaries using the command:
brew install mrswatson