Automatic using ::rtl::OUString etc.

[Tor Lillqvist]

On the other hand, any kind of duplication is always bad, isn't it, as
is inconsistency. So isn't it, from that point of view, bad that some
percentage of the source files contain those "using" statements
(duplication), some a subset of them (inconsistency), others not, some
use ::rtl::foo, others rtl::foo, etc etc. Any changes that would make
the coding style more consistent and less verbose would be good in my
opinion.

--tml