Hello,
conversion to UTF-16BE PDF strings used for example in bookmarks / PDF
outlines is not right.
Take the following example:
```
\starttext
\setupinteraction[state=start]
\placebookmarks[section][number=no]
\section[bookmark=𝕄]
\stoptext
```
Produces: <FEFF0075DD44> for 𝕄 (U+1D544), instead of the correct
<FEFFD835DD44>.
The relevant function is `lpdf.tosixteen()` (from lpdf-ini.lmt), and its
`cache`. (Although the same function is also in lpdf-aux.lmt, and in
MkIV equivalents).
My proposal (also enclosed as a file attachment):
```
--- a/lpdf-ini.lmt
+++ b/lpdf-ini.lmt
@@ -178,7 +178,8 @@
if v < 0x10000 then
v = format("%04x",v)
else
- v = format("%04x%04x",rshift(v,10),v%1024+0xDC00)
+ v = v - 0x10000
+ v = format("%04x%04x",rshift(v,10)+0xD800,v%1024+0xDC00)
end
t[k] = v
return v
```
(Note the similiarity to existing function `big()` in l-unicode.lua.)
I found this by chance, but I am not really a ConTeXt user, so I hope
didn't miss anything.
Regards,
Michal Vlasák
