#7 Fix implementation of assignment operator

[Markus Elfring]

I recommend to add protection for self assignment in classes like "C_DirPath" and "C_PathCopy".
http://esvn.svn.sourceforge.net/viewvc/esvn/trunk/src/dirs_list.cpp?revision=926&view=markup
http://dietmar-kuehl.de/mirror/c++-faq/assignment-operators.html#faq-12.3