Bug 1597 - Enh: Greater clarity over status of versions needed

- For ALPHA builds we do a check version with the Welcome screen (if welcome screen is enabled).
- A 'Check Online' in the About box provides a new route to check version
- Check Version now passes CommitId and Build Date/Time to identify a version.

To actually close the bug we need the javascript on the server page to put up informative messages.

src/AboutDialog.h

@@ -18,6 +18,8 @@
 #include <wx/bitmap.h>
 #include "widgets/wxPanelWrapper.h"
 
+extern const wxString VerCheckArgs();
+
 class ShuttleGui;
 
 struct AboutDialogCreditItem {