Fix previous commit which broke date parsing & palette creation

Hello,

I fixed the previous commit (a73852cb), which was maybe pushed a little bit too fast !

Two things where broken (just by opening a simple trace file):

• date parsing didn't work anymore
• a delete lead to a segfault

Philippe.

src/common/Session.cpp

@@ -286,16 +286,18 @@ void Session::get_palettes_name(const std::string &type, QStringList &list) {
 }
 
 Palette *Session::get_palette(const std::string &type, const std::string &palette_name) {
-    Palette *p = NULL;
-
+    Palette *p, **where_from;
     if( type == "palette" ) {
         p = _palettes_state;
+        where_from = &_palettes_state;
     }
     else if( type == "link_types" ) {
         p = _palettes_link;
+        where_from = &_palettes_link;
     }
     else if( type == "event_types" ) {
         p = _palettes_event;
+        where_from = &_palettes_event;
     }
 
     if(!p || p->get_name() != palette_name) {
@@ -304,6 +306,7 @@ Palette *Session::get_palette(const std::string &type, const std::string &palett
         QMap <QString, QVariant> qmap = S->value(QString::fromStdString(type+"/"+palette_name+"/map")).toMap();
 
         p = new Palette(string(type+"/"+palette_name));
+        *where_from = p;
         for(QMap<QString, QVariant>::const_iterator it = qmap.constBegin() ;
             it != qmap.constEnd() ; ++ it) {
             const QColor qc = it.value().value<QColor>();