.zsh/rc/go.sh: Only push "$HOME/go" to GOPATH if it's unset
.zsh/rc/powerline.sh: Only use powerline on non-cygwin terminals

"cygwin" is the special TERM value used for the windows console. The lack
of font switching on that console makes it completely unsuitable for
powerline, so disable it there.

Also convert tabs to spaces.
.ssh/config: Enable X11 forwarding
.gitconfig: Enable git/warndetachedcommit, sort
.kadr/config.yml: Tweaks to file_naming_scheme