org-odt.el (and org-e-odt.el): Simplify the way style/schema files are found

org-odt.el (and org-e-odt.el): Simplify the way style/schema files are found

* org-odt.el (org-odt-lib-dir, org-odt-data-dir)
(org-odt-schema-dir-list, org-odt-styles-dir-list): Delete.
(org-export-odt-schema-dir, org-odt-styles-dir): Infer the
correct directories without requiring other variables.

* org-fixup.el (org-make-org-version, org-make-autoloads):
Don't define `org-odt-data-dir' in org-version.el.

* contrib/lisp/org-e-odt.el (org-e-odt-lib-dir, org-e-odt-data-dir)
(org-e-odt-schema-dir-list, org-e-odt-styles-dir-list): Delete.
(org-e-odt-schema-dir, org-e-odt-styles-dir): Infer the
correct directories without requiring other variables.