all functions new in Excel since OOXML have _xlfn. prefix

Change-Id: Ie22292da1ee79f2693da73cc27944a53b2213150
moved erroneous _xlfn. from ODFF to OOXML

Change-Id: I58e7d1ba611b4482cfe4ac5f5d37feaf33691a37
Do everything on main thread when the thread count is 1.

This helps debugging / profiling easier.

Change-Id: I7834585bf2aa5d5f550bd218b9845ec964b06655