etc/Makefile: add "schema" to $(ETCDIRS)
contrib/odt/etc/schema/od-manifest-schema-v1.2-cs01.rnc: move to etc/schema/od-manifest-schema-v1.2-cs01.rnc
contrib/odt/etc/schema/od-schema-v1.2-cs01.rnc: move to etc/schema/od-schema-v1.2-cs01.rn
contrib/odt/etc/schema/schemas.xml: move to etc/schema/schemas.xml
Makefile: remove includes for maintainer targets, these will go
into local.mk on the server
default.mk: introduce $(datadir) to replace $(etcdir) in etc/Makefile
doc/Makefile: replace $etcdir) with $(datadir)
lisp/Makefile: record ODT styles location as defconst in org-install
{doc,etc,lisp}/Makefile: prefix all installation targets with $(DESTDIR)