Implement methods of Range

[richardboehme]

Our main approach is to work on one spec from ruby/spec at a time, implementing as much of the spec as possible, then check it off the list:

• [x] begin_spec.rb
• [ ] bsearch_spec.rb
• [x] case_compare_spec.rb
• [x] count_spec.rb
• [x] cover_spec.rb
• [x] dup_spec.rb
• [x] each_spec.rb
• [x] end_spec.rb
• [x] eql_spec.rb
• [x] equal_value_spec.rb
• [x] exclude_end_spec.rb
• [x] first_spec.rb
• [x] frozen_spec.rb
• [x] hash_spec.rb
• [x] include_spec.rb
• [x] initialize_spec.rb
• [x] inspect_spec.rb
• [x] last_spec.rb
• [x] max_spec.rb
• [x] member_spec.rb
• [x] min_spec.rb
• [x] minmax_spec.rb
• [x] new_spec.rb
• [ ] percent_spec.rb
• [x] range_spec.rb
• [x] size_spec.rb
• [ ] step_spec.rb
• [x] to_a_spec.rb
• [x] to_s_spec.rb