GN_Gdt, Convert an ASCII string to an internal binary date

IN:
     HL = source pointer
          0 = read from stream whose handle is IX
          1 = read from filter whose handle is IX
          2 = not allowed
          > 255 = string pointed to by HL
     DE = destination pointer
          0 = not allowed
          1 = not allowed
          2 = result returned in ABC
          >255 = store result at address pointed to by DE
     A = date format
          A0 = 1, undefined
          A1 = 1, undefined
          A2 = 1, undefined
          A3 = 1, force American format (MM/DD/YY)
          A4 = 1, force European format (DD/MM/YY)
          A5 = 1, force C to be the delimiter
          A6 = 1, undefined
          A7 = 1, undefined

     IX = source handle (if HL = 0,1)
     B = maximum number of characters to be read
     C = optional forced delimiter (default is ".")

OUT, if call successful:
     Fc = 0
     HL, if HL(in) = 0, index to last character read
     HL, if HL(in) > 255, pointer to last/terminating character
     ABC, if DE(in) = 2, date in internal format
     ABC, if DE(in) > 255, ABC(in)
     DE, if DE(in) > 255, DE(in)+3
OUT, if call failed:
     Fc = 1
     A = error code:
          RC_ROOM ($07), insufficient memory to make conversion.
          RC_HAND ($08), handles not available for conversion
          RC_BAD ($04), bad parameters
          RC_SNTX ($0C), Bad syntax

Registers changed after return:
     ......../IXIY same
     AFBCDEHL/.... different