FastSerializer: Faster write(OUString): add ascii check

Saves about 80m pcycles for 180k calls.

Change-Id: I9c9b3bf5a076df56d1b5b87f0a85ac3404abe8a4
maTokenNames.size() is constant: use it and be a bit faster

Change-Id: I39a6e2badf0c159e87763e2782bc89f0ee6068ec
optimise UNO Sequence destructor

to avoid expensive function calls until the refcount reaches 0

Signed-off-by: Stephan Bergmann <sbergman@redhat.com>, slightly changing it to
add a uno_type_sequence_destroy to uno/sequence2.h instead of a
uno_type_destructSequence to uno/data.h.

Change-Id: I3bbff3294f2b515fc3c68c4c6c1cb16829f5cc44
(cherry picked from commit d8be5a55760b01efa32708411c6e47fe74600edc)