Fix bug 276268 - “Format not recongnized” Error is displaying while opening...

Fix bug 276268 -  “Format not recongnized” Error is displaying while opening the attached Excel 2010 file

This problem was much more complicated that it looked on the surface.

1. The easy part was that MSO 2010 defines something called
   AlternateContent that defines the same data in two different ways.
   The fallback way is the same as SO 2007 uses, so that's what we try
   to dig out.

2. A more serious problem was that the QUALIFIED_NAME macro was (and
   still is) defined in a way that makes it impossible to use
   READ_PROLOGUE et al. in a file that handles both tags with and
   without namespaces.  See details in MsooXmlCommonReaderImpl.h,
   where the namespace mc starts.

Bug: 276268