Don't bind blocks if not necessary

Binding a block is a performance drawback, replacing blk.call with yield improves performance drastically:

    require 'lotus/view'
    require 'benchmark/ips'

    module Lotus
      module Utils
        class String
          TOKENIZE_REGEXP = /\((.*)\)/
          def fast_tokenize
            if match = TOKENIZE_REGEXP.match(@string)
              pre, post = match.pre_match, match.post_match
              tokens = match[1].split(TOKENIZE_SEPARATOR)
              tokens.each do |token|
                yield(self.class.new("#{pre}#{token}#{post}"))
              end
            else
              yield(self.class.new(@string))
            end

            nil
          end
        end
      end
    end

    string = Lotus::Utils::String.new 'Lotus::(Utils|App)'


    Benchmark.ips do |x|
      x.report("blk.call") do
        string.tokenize do |token|
          token
        end
      end
      x.report("yield") do
        string.fast_tokenize do |token|
          token
        end
      end
    end


Results:

Calculating -------------------------------------
            blk.call     10818 i/100ms
               yield     62064 i/100ms
-------------------------------------------------
            blk.call   127886.5 (±1.7%) i/s -     649080 in   5.076903s
               yield  1091772.8 (±1.5%) i/s -    5461632 in   5.003712s