LilyPond Windows installer entirely erases the PATH environment variable

[Zachary Northrup]

I recently installed LilyPond for Windows and soon after noticed that a ton of
development tools stopped working. I then discovered that LilyPond's Windows
installer had completely erased my PATH environment variable and replaced it
with the LilyPond path. Thankfully for me, Windows keeps environment variables
in the backup system control set in the registry, so I was able to find the old
variable and replace it myself.

I then reinstalled LilyPond to verofy that it was, in fact, LilyPond's
installation that caused the variable corruption, and it was.

This is a *serious* corruption of the user environment. The LilyPond for Windows
installer should be rescinded immediately to prevent further data loss. I also
note that the installer never once asked the user whether they even wanted the
PATH variable modified. As a best practice, it should default to /not/ modifying
the variables, unless the user asks for it.