Updated/fixed ProgressDialog for wx3

This also re-enables the splash screen and recombines the
OnInit() and FinishInits() since I'm pretty sure the progress
dialog was the issue.

I also retested (as much as I could) and cleaned out all of the
little "hacks" the progress dialog gained over the years.  With
the new modal handling of wx3, it seems that things are much better
behaved.

However, it seems that wxGTK (at least) has gained some new focus
probs (to be dealt with later).

src/AudacityApp.cpp

@@ -1308,15 +1308,6 @@ bool AudacityApp::OnInit()
 // If we're waiitng in a dialog before then we can very easily
 // start multiple instances, defeating the single instance checker.
 
-
-
-
-   //JKC We'd like to initialise the module manager WHILE showing the splash screen.
-   //Can't in wx3.0.1 as MultiDialog interacts poorly with the splash screen.  So we do it before.
-   //TODO: Find out why opening a multidialog wrecks the splash screen.
-   //best current guess is that it's something to do with doing a DoModal this early
-   //in the program.
-
    // Initialize the CommandHandler
    InitCommandHandler();
 
@@ -1375,9 +1366,6 @@ bool AudacityApp::OnInit()
       exit(1);
    }
 
-// No Splash screen on wx3 whislt we sort out the problem
-// with showing a dialog AND a splash screen during inits.
-#if !wxCHECK_VERSION(3, 0, 0)
    // BG: Create a temporary window to set as the top window
    wxImage logoimage((const char **) AudacityLogoWithName_xpm);
    logoimage.Rescale(logoimage.GetWidth() / 2, logoimage.GetHeight() / 2);
@@ -1394,7 +1382,6 @@ bool AudacityApp::OnInit()
                          wxSTAY_ON_TOP);
    temporarywindow->SetTitle(_("Audacity is starting up..."));
    SetTopWindow(temporarywindow);
-#endif
 
    //JKC: Would like to put module loading here.
 
@@ -1444,11 +1431,8 @@ bool AudacityApp::OnInit()
       pWnd->Show( true );
    }
 
-
-#if !wxCHECK_VERSION(3, 0, 0)
    temporarywindow->Show(false);
    delete temporarywindow;
-#endif
 
    if( project->mShowSplashScreen )
       project->OnHelpWelcome();