prevents crash when part is not found or pdf couldn't be opened,

also nothing will be added to recent files in that case
thx domi

svn path=/trunk/kdegraphics/kpdf/; revision=275961

kpdf/kpdf_shell.cpp

@@ -81,8 +81,7 @@ Shell::~Shell()
 
 void Shell::openURL( const KURL & url )
 {
-    m_part->openURL( url );
-    recent->addURL (url);
+    if ( m_part->openURL( url ) ) recent->addURL (url);
 }