Hello,
I'm trying to get a callback function working with arguments under the new
API. 

Problems:
1. The example in callbacks-example-filename2.c still documents usage as the
old API in several places. 
2. HTS_LIBDIR doesn't appear to be defined by the configure script/Makefile to
the location where the callback libraries are installed, so it defaults to
/usr/lib. 
3. Contrary to usage documentation which suggests "httrack --wrapper
mycallback" will work for mycallback.so, it appears to be necessary to specify
the full filename (including the .so). So thanks to 2 and 3, the actual usage
seems to be "--wrapper /full/path/to/mycallback.so". This works for callbacks
that don't require arguments.
4. Passing arguments
like "httrack --wrapper /full/path/to/libfilename2.so,args", which is
documented as the correct way to pass args in
<http://www.httrack.com/html/plug.html>, doesn't work: it complains it can't
find the module /full/path/to/libfilename2.so,args (ie it doesn't seem to
split off the comma and the args before trying to find the file)