get rid of excess functions in World

remove World::ActiveBlock(ushort, ushort, ushort) and
World::HasInventory(ushort, ushort, ushort). Use World::GetBlock(ushort,
ushort, ushort)->ActiveBlock() and ...->HasInventory() instead.
code chore

static constants to UPPER_CASE, make line width in Player.cpp <=79.
code chore

Remove excess includes, class predeclarations, add licence to
DeferredActions.cpp.