Proposal to introduce "port select ruby"

[kimura wataru]

Hi,

Last month, ruby-2.0 was released. I think we need "port select ruby"
before add port:ruby20.
I made some patches for "port select ruby".
https://github.com/kimuraw/macports-port-select-ruby

Can I merge them to MacPorts' repository?

## Abstract

- add port:ruby_select
- avoid conflicts between port:ruby and port:ruby19
    - add suffix "1.8" to commands of port:ruby. (bin/ruby1.8)
- avoid conflicts between port:rb-* and port:rb19-*. 
  install commands like perl5's p5.nn-*, such as port:p5.12-app-ack.
    - commands without suffix under ${prefix}/libexec/ruby${branch}/
    - suffixed commands under ${prefix}/bin/

## file hierarchy

	${prefix}/bin
	    ruby1.8        - port:ruby
	    ruby1.9        - port:ruby19
	    nanoc3-1.8     - port:rb-nanoc3
	    nanoc3-1.9     - port:rb19-nanoc3
	${prefix}/libexec/
	    ruby1.8/nanoc3 - port:rb-nanoc3
	    ruby1.9/nanoc3 - port:rb19-nanoc3
	${prefix}/etc/select/ruby
	    base           - port:ruby_select
	    none           - port:ruby_select
	    ruby18         - port:ruby
	    ruby19         - port:ruby19

-- 
kimura wataru