good-bye stringex, you served well

It will be better to handle Android Impress Remote localization
independent of the big LibreOffice source tree. Instead of
stringex, we will use android2po, a 3rd party utility for conversion
strings.xml <-> pot/po.

Change-Id: I4eae53e4f8d94c55e5564d54c5e5c214bc9569d7