Add code from merging.

This brings more of the code from DarkAudacity into Audacity, though not yet enabled.  This will make cherry picking later easier.
- Changing colour of html displays now possible, as colour links are visible for substitution.  (Can't use css as wxHTML is very limited).
- Export can now be preset to a particular format independent of preferences.
- SnapTo reversion on zoom now a DA controlled option.
- Caching of pinning preference for faster repaint because preferences are slow.
- Record Append now has sensible limit on number of tracks, rather than giving an error, and flipping the meaning of shift is now DA controlled.

src/export/Export.cpp

@@ -265,6 +265,7 @@ Exporter::Exporter()
 {
    mMixerSpec = NULL;
    mBook = NULL;
+   mFormatName = "";
 
    SetFileDialogTitle( _("Export Audio") );
 
@@ -488,7 +489,9 @@ bool Exporter::GetFilename()
    mFormat = -1;
 
    wxString maskString;
-   wxString defaultFormat = gPrefs->Read(wxT("/Export/Format"),
+   wxString defaultFormat = mFormatName;
+   if( defaultFormat.IsEmpty() )
+      defaultFormat = gPrefs->Read(wxT("/Export/Format"),
                                          wxT("WAV"));
 
    mFilterIndex = 0;
@@ -678,7 +681,8 @@ bool Exporter::CheckFilename()
    if (!mProject->GetDirManager()->EnsureSafeFilename(mFilename))
       return false;
 
-   gPrefs->Write(wxT("/Export/Format"), mPlugins[mFormat]->GetFormat(mSubFormat));
+   if( mFormatName.IsEmpty() )
+      gPrefs->Write(wxT("/Export/Format"), mPlugins[mFormat]->GetFormat(mSubFormat));
    gPrefs->Write(wxT("/Export/Path"), mFilename.GetPath());
    gPrefs->Flush();
 

src/export/Export.h

@@ -144,6 +144,7 @@ public:
    virtual ~Exporter();
 
    void SetFileDialogTitle( const wxString & DialogTitle );
+   void SetDefaultFormat( const wxString & Format ){ mFormatName = Format;};
    void RegisterPlugin(movable_ptr<ExportPlugin> &&plugin);
 
    bool Process(AudacityProject *project, bool selectedOnly,
@@ -173,7 +174,7 @@ public:
    wxFileName GetAutoExportFileName();
 
 private:
-
+   wxString mFormatName;
    bool ExamineTracks();
    bool GetFilename();
    bool CheckFilename();