Log Message:
Update devel/ruby-parsetree to 3.0.6.

* Use lang/ruby/gem.mk instead of misc/rubygems/rubygem.mk.
* Update dependency according to gemspec.

=== 3.0.6 / 2010-09-01

* 1 bug fix:

  * fixed requires (e-tobi)

=== 3.0.5 / 2010-03-27

* 1 bug fix:

  * Fixed NODE_METHOD but also commented that you shouldn't ever see it \ 
naturally (tmm1)