manager now has two extra parameterless procedures (ThreadInitProc
and ThreadFiniProc) which are called whenever a thread begins/ends,
and cwstring uses these to create separate iconv handles for
each thread (via threadvars)
* renamed UCS4 to UCS-4BE/LE, because UCS4 is not recognised by most
systems
* clean up all iconv handles on exit, and check whether they are
valid before doing so
git-svn-id: trunk@7949 -