[ft] FTC_CMapCache_Lookup() migration

[Ian Britten]

Hi all,
In our v2.1.7 code, we're calling FTC_CMapCache_Lookup(),
and what we pass in is different, depending on a higher-level
'useUnicode' parameter that is passed in (which I'm still
tracing/investigating - It seems to be 'true' in most cases...).

The relevant code is like this:
        FTC_CMapDescRec  desc;
        desc.face_id = theFace;
        if (useUnicode)
        {
                desc.type = FTC_CMAP_BY_ENCODING;
                desc.u.encoding = ft_encoding_unicode;
        }
        else
        {
                desc.type = FTC_CMAP_BY_INDEX;
                desc.u.index = 0;
        }
        return FTC_CMapCache_Lookup(
              theCache, &desc, inCharcode);

I'm trying to upgrade the code to the latest v2.3.5, and it
seems that all traces of this stuff is gone (FTC_CMapDescRec,
FTC_CMAP_BY_*, etc).

I can update the code to call the new FTC_CMapCache_Lookup()
easy enough(*), but I'm left with this unused 'useUnicode'
input parameter.  I'm unsure whether I should be trying to add
more (unknown) code to account for the parameter, or whether I
should be trying to remove the parameter and altering the
callers somehow.

[(*) Maybe.  I'm not entirely sure where I'm to come up with
the cmap_index parameter, and just have a zero for now.  Maybe
the answer to that is related to my main questions? ]

- Is the default now FTC_CMAP_BY_ENCODING?  Presumably it
  must be one or the other, I would guess....
- If I need to provide similar control (Still investigating),
  where/how would I do it?
- Or, is this something that shouldn't be needed, is outside
  the scope of FT, etc. ?

Thanks for any information!
Ian