What is the simplest way to download and set path variables for D compilers when using AppVeyor

[Michael Brockus]

I am wondering if you guys would know what maybe the simplest way 
to have D working on AppVeyor because I already have a solution 
for both CircleCi, Travis-Ci and wish to expand to windows.

Also as tip for Meson build users Ninja is available on PyPi 
meaning that you can have a simple command like "pip install 
meson ninja --user" and it would work.  Also less lines of Yaml 
to maintain plus readability.