AUP3: Don't delete sample blocks prematurely

The wrong sample blocks would be deleted at close in step 6:

1) New Project
2) Save and name
3) Import one stereo MP3 (about 6 minutes)
4) Save, close and re-open
5) Apply Bass and Treble to the track using real-time preview
6) Save, close and re-open
7) Message Failed to retrieve sample block

src/ProjectFileIO.cpp

@@ -2162,7 +2162,7 @@ AutoCommitTransaction::~AutoCommitTransaction()
 {
    if (mInTrans)
    {
-      if (!mIO.TransactionRollback(mName))
+      if (!mIO.TransactionCommit(mName))
       {
          // Do not throw from a destructor!
          // This has to be a no-fail cleanup that does the best that it can.
@@ -2170,13 +2170,13 @@ AutoCommitTransaction::~AutoCommitTransaction()
    }
 }
 
-bool AutoCommitTransaction::Commit()
+bool AutoCommitTransaction::Rollback()
 {
    if ( !mInTrans )
       // Misuse of this class
       THROW_INCONSISTENCY_EXCEPTION;
 
-   mInTrans = !mIO.TransactionCommit(mName);
+   mInTrans = !mIO.TransactionRollback(mName);
 
    return mInTrans;
 }

src/ProjectFileIO.h

@@ -221,8 +221,6 @@ private:
 };
 
 // Make a savepoint (a transaction, possibly nested) with the given name;
-// roll it back at destruction time, unless an explicit Commit() happened first.
-// Commit() must not be called again after one successful call.
 // An exception is thrown from the constructor if the transaction cannot open.
 class AutoCommitTransaction
 {
@@ -230,7 +228,7 @@ public:
    AutoCommitTransaction(ProjectFileIO &projectFileIO, const char *name);
    ~AutoCommitTransaction();
 
-   bool Commit();
+   bool Rollback();
 
 private:
    ProjectFileIO &mIO;

src/ProjectManager.cpp

@@ -748,8 +748,6 @@ void ProjectManager::OnCloseWindow(wxCloseEvent & event)
 
       // Delete all the tracks to free up memory
       tracks.Clear();
-
-      trans.Commit();
    }
 
    // We're all done with the project file, so close it now

src/effects/Effect.cpp

@@ -1251,9 +1251,6 @@ bool Effect::DoEffect(double projectRate,
          // LastUsedDuration may have been modified by Preview.
          SetDuration(oldDuration);
       }
-      else
-         trans.Commit();
-
       End();
       ReplaceProcessedTracks( false );
    } );