update: according the new API of Package

[rtrepos]

• taking into account the version of vle without the Package singleton
• disable pyvle_open without the specification of a package

[quesnel]

I can't merge this patch:

std::string logfilename = utils::Trace::getLogFilename("pyvle.log");
std::ofstream* logfile = new std::ofstream(logfilename.c_str());
(*logfile) << _("Error: pyvle_open whitout the specfication of a package "
        "is not possible")
                << "\n\n" << std::flush;

• Memory leaks with the logfile pointer.
• The message can be view for user only if he open the $VLE_HOME/pyvle.log file.
• The return is missing.

So I recommend you to remove this useless function.