Extend picture() and savedocx() to save pictures without copying them to
the template directory. When the same image file is used multiple times,
no duplicates will be added.

Caveat: to prevent image files from accumulating in word/media/ across
runs, never call picture() and savedocx() without the imagefiledict
parameter. The imagefiledict is optional because of backward compatibility.
Apply EXIF orientation information in the rot, flipH and flipV properties of
the xfrm element when creating the shape properties of an image.

See: http://www.schemacentral.com/sc/ooxml/e-p_xfrm-1.html
Corrected the creation of picrelid and unique filenames, usage of
picdescription instead of picname in creating the cNvPr element, and
removed an invalid reference from the template.
Added PendingDeprecationWarning for the code sections which ensure
backward compatibility.