Reuse PATH variable in --path output

[kgraefe]

With that change using --path gives something like

export PATH="/cygdrive/c/Users/me/pidgin/win32-dev/mingw-gcc-4.7.2/bin:/cygdrive/c/Users/me/pidgin/win32-dev/strawberry-perl-5.20.1/perl/bin:/cygdrive/c/Users/me/pidgin/win32-dev/nsis-2.46:${PATH}"

I don't know if you like that, but for me it is better to see what actually changes. printf "%q" "..." takes care of the escaping.

Also I have this habbit of putting environment files in my project directories. In that case, changes I do to PATH later will also be inherited.