Convert a string to upper or lower case astChrCase
" out" string are used as the input string. " blen" . If NULL is supplied for " in" , then the supplied
contents of " out" are converted and written back into " out" over-writing the
supplied contents. " in" is NULL. No more than " blen - 1" characters will be copied
from " in" to " out" , and a terminating null character will then be added.