Require svg support for linked and inline images

TIghten the prose such that supporting SVG both for linked, as well as embedded (e.g. 10.4.5 <office:binary-data>) is required for odf compliant consumers

References: https://lists.oasis-open.org/archives/office-comment/200903/msg00155.html (section numbers at the bottom seem to be off)
and
http://idippedut.dk/post/Embrace-and-extend-SVG-revisited