st.hpp: Remove extra ';'

Qt Creator was complaining about them
Remove unused st_* definitions from Packer*.cpp
st.hpp: Remove some more extra ';'

Forgot to remove them
st.hpp: Remove unused st_ wrappers for primitive types
Rename spriteinfo to Sprite
Move some sound/sprite specific stuff to sound/sprite.*pp
Remove useless p_abs()
Packer*.cpp: Remove unused OFFSETOF and friends
Packer*.cpp: Remove unused Array and friends