Remove more uses of at(); use a std::vector of bare pointers, not wx array

src/Dependencies.cpp

@@ -75,7 +75,7 @@ static void GetAllSeqBlocks(AudacityProject *project,
             BlockArray &blocks = sequence->GetBlockArray();
             int i;
             for (i = 0; i < (int)blocks.size(); i++)
-               outBlocks->push_back(&blocks.at(i));
+               outBlocks->push_back(&blocks[i]);
             node = node->GetNext();
          }
       }

src/Project.cpp

@@ -10,7 +10,7 @@
 *******************************************************************//**
 
 \file Project.cpp
-\brief Implements AudacityProject, DropTarget, and FileObject.
+\brief Implements AudacityProject, DropTarget, and FileObject.F
 Includes Menus.cpp.
 
 *//****************************************************************//**
@@ -3738,7 +3738,7 @@ void AudacityProject::AddImportedTracks(wxString fileName,
          BlockArray &blocks = clip->GetSequence()->GetBlockArray();
          if (clip && blocks.size())
          {
-            SeqBlock& block = blocks.at(0);
+            SeqBlock& block = blocks[0];
             if (block.f->IsAlias())
             {
                mImportedDependencies = true;

src/Sequence.h

@@ -53,7 +53,7 @@ class SeqBlock {
    }
 };
 class BlockArray : public std::vector<SeqBlock> {};
-WX_DEFINE_ARRAY(SeqBlock *, BlockPtrArray);
+using BlockPtrArray = std::vector<SeqBlock*>; // non-owning pointers
 
 class Sequence: public XMLTagHandler {
  public:

src/UndoManager.cpp

@@ -82,7 +82,7 @@ void UndoManager::CalculateSpaceUsage()
             BlockArray *blocks = it->GetData()->GetSequenceBlockArray();
             for (size_t b = 0, cnt = blocks->size(); b < cnt; b++)
             {
-               BlockFile *file = blocks->at(b).f;
+               BlockFile *file = (*blocks)[b].f;
 
                // Accumulate space used by the file if the file didn't exist
                // in the previous level

src/ondemand/ODComputeSummaryTask.cpp

@@ -205,7 +205,7 @@ void ODComputeSummaryTask::Update()
             for(i=0; i<(int)blocks->size(); i++)
             {
                //if there is data but no summary, this blockfile needs summarizing.
-               SeqBlock &block = blocks->at(i);
+               SeqBlock &block = (*blocks)[i];
                BlockFile *const file = block.f;
                if(file->IsDataAvailable() && !file->IsSummaryAvailable())
                {

src/ondemand/ODDecodeTask.cpp

@@ -157,7 +157,7 @@ void ODDecodeTask::Update()
             for (i = 0; i<(int)blocks->size(); i++)
             {
                //since we have more than one ODBlockFile, we will need type flags to cast.
-               SeqBlock &block = blocks->at(i);
+               SeqBlock &block = (*blocks)[i];
                BlockFile *const file = block.f;
                ODDecodeBlockFile *oddbFile;
                if (!file->IsDataAvailable() &&