Add about reinplace target
Add dir port-step0 (before changing)
Copyt port-step0 to port-step1
Add generating libxec dir for port:ruby and port:ruby19
Add .gitignre
Support intallation under libexec for ruby.setup gem
Remove conflicts from port:rb19-nanoc3
Support installation under libexec for ruby.setup setup.rb
Support installation under libexec for "ruby.setup gnu"

"ruby.setup gnu" is used only in port:rb-pdumpfs.