Rockbox

This patch improves Tremor performance by a few percent
compared to what is in CVS currently.

I created this patch based on advice from devs, and
profiling results. The strategy I followed was to put
all data arrays into IRAM first, except those which
were identified as not being used in current encodings
by IRC:Lear. Then I used profiling results, and nm
-BnS output to determing which parts of code were
causing cache thrashing, and moved those parts to IRAM
where they could be called rapidly without trashing the
cache for other more often used or smaller functions.
Finally, I inlined two of the three remaining most
called functions by combining bitwise.c and codebook.c
into codebook.c. The remaining most called function
was not easily inlinable, it is vorbis_book_decodevv_add.

That function and oggpack_look and oggpack_adv would be
great candidates for further optimization, along with
the mdct that I believe someone is already working on.