Update for AVRDUDE 6.4

[milelo]

Avrdude 6.4 is available http://download.savannah.gnu.org/releases/avrdude/avrdude-6.4-mingw32.zip.
move contents to:
C:\Program Files (x86)\avrdude-6.4.
add this to systems path and refresh using:
$env:Path = [System.Environment]::GetEnvironmentVariable("Path","Machine")
WinAVR isn't required.
I've tested 6.4 and confirmed compatibility.

See also https://community.chocolatey.org/packages/avrdude as a Windows install option for V6.3

For osx brew mention installed package versions can be selected by unlinking package and linking package@version.