When parsing yaml files, also parse native environment syntaxes right

When schema 2 for the yaml files introduced environment variables, the code has to take into account different syntaxes in Windows and Linux world. Currently environment variables are quoted by saying $PATH, even though windows world handles them by saying %PATH%. The path delimiter however is semicolon ( just as it is in the windows realm, and colon ( does not work there. So the current way of presenting things "is PATH=/foobar/;$PATH" which is a mixture of windows and unix syntaxes.

What we perhaps do is support "PATH=/foobar/;%PATH%", or have it always in the linux style "PATH=/foobar/:$PATH" and then code translates it into windows syntax.