Reduce array allocations in Roo::Utils.each_element

[will89]

Summary

Taking some of the memory improvement changes from #436. This reduces the number of array allocations in Roo::Utils.each_element when the elements argument is not an Array.

Memory profiling against the file test/files/Bibelbund.xlsx

Master
Total allocated: 42492082 bytes (555917 objects)
Total retained:  1295107 bytes (11631 objects)

allocated memory by gem
-----------------------------------
  21031985  roo-rb-roo/lib
  11231729  nokogiri-1.8.5
  10226503  rubyzip-1.2.2
      1433  tmpdir
       240  weakref
       192  other

This PR
Total allocated: 40143162 bytes (497194 objects)
Total retained:  1295107 bytes (11631 objects)

allocated memory by gem
-----------------------------------
  18683065  will89-roo/lib
  11231729  nokogiri-1.8.5
  10226503  rubyzip-1.2.2
      1433  tmpdir
       240  weakref
       192  other

This PR used about ~16% less memory when iterating through the file and allocated ~10% fewer objects.

# frozen_string_literal: true

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  #gem "roo", path: '/Users/will/repos/will89-roo'
  gem "roo", path: '/Users/will/repos/roo-rb-roo'
  gem "minitest"
  gem "memory_profiler"
end

require "roo"
require "minitest/autorun"
require "memory_profiler"

class BugTest < Minitest::Test
  def test_stuff
    # add your test here
    report = MemoryProfiler.report do
      sheet = Roo::Spreadsheet.open("/Users/will/repos/will89-roo/test/files/Bibelbund.xlsx", no_hyperlinks: true)
      sheet.each_row_streaming do |row|
        row[1]
      end
    end
    report.pretty_print
  end
end

[coveralls]

Coverage increased (+0.04%) to 94.098% when pulling 467f163 on will89:improve-utils-each_element into 5fc4378 on roo-rb:master.

[coveralls]

Coverage increased (+0.04%) to 94.098% when pulling 467f163 on will89:improve-utils-each_element into 5fc4378 on roo-rb:master.