writerfilter: initial strict DOCX support

The generate-id() code is just necessary avoid duplicated elements in
the for-each loop. http://mahahegde.com/xslt-distinct-values/ has a
detailed description of the technique used here.
(cherry picked from commit f9bf15e19ec823a58ee32bf94da81f3bb1a147bc)

writerfilter: introduce ooxml::OOXMLUniversalMeasureValue

In transitional DOCX, ST_UniversalMeasure is in practice a simple integer,
which means twips. But in case of strict, ST_UniversalMeasure is in points
in practice -- which is perfectly valid, but we didn't handle it so far.

Add a separate Value class that is used only for handling
ST_UniversalMeasure, then there we can handle the various additional
suffixes.
(cherry picked from commit d5d7c7d3b281e1a9060d60bc4ac7738ae616f167)

DOCX import: handle points in ST_TwipsMeasure and ST_SignedTwipsMeasure

This fixes page size and margins in case of strict DOCX.
(cherry picked from commit 37cc7e7471ba3b11cefcb0218c27e2c745886a6d)

DOCX strict import: fix headers

Now that the document has a header, better to just test the bottom
margin, as in case there is a header, the top margin has different
semantics in Word and Writer.
(cherry picked from commit 195b8491d0299038fb64d19463e3ce90905bf346)

DOCX strict import: fix pictures as well
(cherry picked from commit aaef39de32442203d631a65aecf23eeb27dfbb12)

DOCX strict import: handle charts
(cherry picked from commit 49c3aff8d8d3030b2acbffb6ff000b5d44445cc9)

DOCX strict import: handle SmartArt
(cherry picked from commit f5985685ddc519f760a7324fa60fd662f25404c1)

DOCX strict import: handle lockedCanvas
(cherry picked from commit d795fb224e52c66c4585ed1e079a2b7601a07eda)

DOCX strict import: handle math
(cherry picked from commit c98d649117dc776ac51807be3376924d1fce2035)

Conflicts:
	sw/qa/extras/ooxmlimport/ooxmlimport.cxx

Change-Id: I647efe9d4a0834d3756fe9fa6d706ba6ba4e00f1
Reviewed-on: https://gerrit.libreoffice.org/8532
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>