Make Transcription ToolBar resizable.

I moved 'Fit()' from ToolBars into MeterToolBar, because it is a workaround for an incorrect size calculation by MeterToolBar.  MeterToolBar is sized as if there is no resizer, so when there is one, the toolbar needs to be expanded (using Fit) to accommodate the resizer.

I also set the min size of MeterToolBar to 150, so that some meter will appear, even if Toolbar shrunk to the minimum.

src/toolbars/ToolBar.cpp

@@ -586,7 +586,6 @@ void ToolBar::SetDocked( ToolDock *dock, bool pushed )
    {
       mResizer->Show(dock != NULL);
       Layout();
-      Fit();
    }
 }