tiny API changes, some small bugfixes, webvtt_bytearray fused into webvt...

...t_string, etc...

-- This all builds on MSVC2010 and GCC 4.5.2 here, however I can't guarantee there won't be problems on other systems, and it will thoroughly fail any valgrind memchecks for a while. A lot of formerly passing tests are now failing, but I got it to not crash at least (on my end)