Fix compile error with ruby-2.0 [WIP]

this change is WIP. config and setup works, but not work.

- fix importing header file, such as <ruby/ruby.h>
- fix renamed symbols:
  - rb_frame_last_func -> rb_frame_this_func
  - ruby_errinfo -> rb_errinfo
  - is_ruby_native_thread -> ruby_native_thread_p
- use alternate values for missing symbols:
  - rb_load_path, rb_thread_critical

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2456 f4f36d40-9719-0410-9868-dde021a23eda
Allow "install.rb config" with ruby-2.0

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2457 f4f36d40-9719-0410-9868-dde021a23eda
Fix errors with ruby-2.0 from difference between 2.0 and 1.8

- String#each -> String#each_line
- require 'curdir_file' -> require './curdir_file'

git-svn-id: https://svn.code.sf.net/p/rubycocoa/svn/trunk/src@2458 f4f36d40-9719-0410-9868-dde021a23eda