writerfilter: Kill AttributeToResourceMap.

IMPORTANT: From now on, the order of attributes becomes stable, based on the
order in model.xml (not on implementation details of unordered_map), and the
code that handles attributes may depend on a particular order.  If you want to
change the order how the attributes are handled, change model.xml, and check
you achieved what you wanted in the generated ::getAttributeInfoArray()'s.

[Writerfilter loses another 250k (stripped dbgutil).  And the usage of
unordered_map here was just completely bogus from the very beginning, as it
was only iterated as a normal array anyway ;-)]

Change-Id: Ic70c37793e313c4ccda1d6f374cc2d366307ba1b
writerfilter: This depended on the order of attributes.

This code actually worked by mistake, thanks to the wrong ordering of
attributes that was caused by the usage of the boost::unordered_map.

Change-Id: I72cc5b54496b03183987d4d004f985d368e63deb
Revert "ugly hack for NS_ooxml::LN_CT_Style_type being the first attribute...

I believe this is not necessary after the recent removal of unordered_map from
handling the attributes.

This reverts commit 76336334e669519cfa42413b851584fa321c004d.

Change-Id: I631bc2613954953a30448dbe2a5bf564c529e2a0