changed array_rand.rb -> rand.rb

changed array_rand.rb(成澤さんが新しく作ったものに変更)

changed register.rb

changed ascii.rb(delete comment)

changed array.rb, array_rand.rb

add banner.rb, quizmihon.rb, stopwatch.rb

changed beginning of program to #!/usr/bin/env ruby

changed name from link to lectures, changed the directory name of *.html 授業リンク集 from link to lectures