Fix Memory Exhaustion on Mass Import/Sync

.. RideCache::addRide() deletes the prior ride, which is rather meaningless
   if you are just importing a ride, but when syncing large numbers
   of rides will stop memory being exhausted.

.. similarly in the FileStoreSyncDialog we now free up the memory
   used to read the downloaded files before moving on to the next.

src/FileStore.cpp

@@ -1098,7 +1098,7 @@ FileStoreSyncDialog::downloadNext()
             rideListDown->setCurrentItem(curr);
             progressLabel->setText(QString(tr("Downloaded %1 of %2")).arg(downloadcounter).arg(downloadtotal));
 
-            QByteArray *data = new QByteArray;
+            QByteArray *data = new QByteArray; // gets deleted when read completes
             store->readFile(data, curr->text(1));
             QApplication::processEvents();
             return true;
@@ -1145,7 +1145,8 @@ FileStoreSyncDialog::completedRead(QByteArray *data, QString name, QString messa
     // uncompress and parse
     QStringList errors;
     RideFile *ride = store->uncompressRide(data, name, errors);
-    
+
+    // was allocated in before calling readfile
     delete data;
 
     progressBar->setValue(++downloadcounter);
@@ -1158,6 +1159,9 @@ FileStoreSyncDialog::completedRead(QByteArray *data, QString name, QString messa
         } else {
             curr->setText(col, errors.join(" "));
         }
+
+	// delete once saved
+	delete ride;
     } else {
         curr->setText(col, errors.join(" "));
     }

src/RideCache.cpp

@@ -164,6 +164,8 @@ RideCache::itemChanged()
 void
 RideCache::addRide(QString name, bool dosignal, bool useTempActivities)
 {
+    RideItem *prior = context->ride;
+
     // ignore malformed names
     QDateTime dt;
     if (!RideFile::parseRideFileName(name, &dt)) return;
@@ -201,6 +203,11 @@ RideCache::addRide(QString name, bool dosignal, bool useTempActivities)
 
     if (dosignal) context->notifyRideAdded(last); // here so emitted BEFORE rideSelected is emitted!
 
+    // free up memory from last one, which is no biggie when importing
+    // a single ride, but means we don't exhaust memory when we import
+    // hundreds/thousands of rides in a batch import.
+    if (prior) prior->close();
+
     // notify everyone to select it
     context->ride = last;
     context->notifyRideSelected(last);

src/RideItem.cpp

@@ -401,12 +401,23 @@ RideItem::isOpen()
 void
 RideItem::close()
 {
+    // ride data
     if (ride_) {
         // break link to ride file
         foreach(IntervalItem *x, intervals()) x->rideInterval = NULL;
         delete ride_;
         ride_ = NULL;
     }
+
+    // and the cpx data
+    if (fileCache_) {
+    	delete fileCache_;
+	fileCache_=NULL;
+    }
+
+    // and the intervals
+    foreach(IntervalItem*x, intervals_) delete x;
+    intervals_.clear();
 }
 
 void