First steps to organize an importer that can read/interpret
wmf/emf/emf+ and deliver a primitive representation for
the content by parsing it. Use the same mechanisms as
already applied for Svg, so to reuse abilities to keep
original binary data to allow save again and embedding in
files and have an implemented replacement bitmap based
representation. For this, unify the used helper classes
to handle more than just Svg. For 1st try, add test code
and static bool switches

Change-Id: I6e0a82943541d811a8f8d65a84115569fcd8cee7