This commit removes ::rtl:: prefixes and string cleanup in oox

Change-Id: I434462635392c750e2359f9d656d5e1885f2a0dc
Signed-off-by: Jose Guilherme Vanz <guilherme.sft@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/1520Reviewed-by: LOH KOK HOE <huahsin68@gmail.com>
Reviewed-by: Miklos Vajna <vmiklos@suse.cz>
Tested-by: Miklos Vajna <vmiklos@suse.cz>