When creating dependency graphs using dot, quotes are not escaped during
writing of the .dot file.  Trying to document this piece of code

//! unbalanced " quote
class t {
};

class t2 : t {
};

has doxygen break with the following error:

Warning: /tmp/doxy/html/inherit__graph__0.dot:6: string ran past end of line
Error: /tmp/doxy/html/inherit__graph__0.dot:7: syntax error near line 7
context:   Node1 >>>  -> <<<  Node2 [dir=back,color="firebrick4",fontsize="10",style="solid",fontname="FreeSans.ttf"];
Problems running dot: exit code=1, command='dot', arguments='"/tmp/doxy/html/inherit__graph__0.dot" -Tpng -o "/tmp/doxy/html/inherit__graph__0.png" -Tcmapx -o "/tmp/doxy/html/inherit__graph__0.map"'
finished...

Cheers,