cleanup array.rb (move to mrbgems/mruby-array-ext)
cleanup hash.rb (move to mrbgems/mruby-hash-ext)
cleanup numeric (move to mrbgems/mruby-numeric-ext)

 - Integer#chr has alredy moved to mrbgems/mruby-numeric-ext.
cleanup String#getbyte (move to mrbgems/mruby-string-ext)

 - String#getbyte has already move to mrbgems/mruby-string-ext.
cleanup Nil#to_a, to_f, to_i (move to mrbgems/mruby-object-ext)
cleanup string.rb (move to mrbgems/mruby-string-ext)

 - String#lstrip, #rstrip, #strip, #lstrip!, #rstrip!, #strip!
remove test/t/ipaddr.rb (move to iij/mruby-ipaddr gem)