writerfiler: define DEBUG_DMAPPER_GRAPHIC_IMPORT when dbglevel == 2

Change-Id: I8cfdb020d2b3e8ad886c0a9507e4eb8d0a29f87d
DOCX import: initial support for wp14:sizeRelH/V relativeFrom

For now just warn on unexpected values, and ignore margin, what is the
only value supported by Writer.

Change-Id: Ia4fc7293839610c1bbe2dceda2320a5ba2d3a15b