Convert a string to upper or lower case

Added by iNTERFACEWARE

Convert a string to upper case with string.upper(), or lower case with string.lower()

Source Code
   -- convert a string to upper case
   local s = 'hello world'
   s = s:upper()
   --> 'HELLO WORLD'

   -- convert a string to lower case
   local s = 'HELLO WORLD'
   s = s:lower()
   --> 'hello world'