Translate bif added.

[Peter-Jacob]

I added the translate bif: commit 0937f3b. Comment refers to date bif, which is wrong!

I implemented actually 2 versions of it, a plain rexx, and one with a new TRANSCHAR instruction:

   transchar schar,tochar,fromchar 
   schar   is one source character of the source string
   tochar is the translate "change-to-char-list"
   fromchar the translate "from-char-list" 

there are all parameters of translate supported, except an empty from-char-list. In ANSI it means it defaults to the 256-byte ANSI character set. Doesn't make much sense in UTF8.

The first plain rexx version was this:

/* rexx */
options levelb

translate: procedure = .string
  arg expose source = .string, tochar = .string, fromchar = .string
  slen=0
  tlen=0
  flen=0
  target=""
  fchar=0
  tchar=0
  schar=0
  assembler strlen slen,source    /* get length of souce string */
  assembler strlen flen,fromchar  /* get length of from char string */
  assembler strlen tlen,tochar    /* get length of to char string */
  do i=0 to slen-1                /* run through from source string */
     assembler strchar schar,source,i
     do j=0 to flen-1
        assembler strchar fchar,fromchar,j
        if schar=fchar then do
           assembler strchar tchar,tochar,j
           schar=tchar
           leave
        end
     end
     assembler appendchar target,schar
  end
return target