OPTIMIZATION: Shared the jumpTable computed for switch statements within a task.

Previously, each *instance* of a task would recompute its own jump tables,
though they would be cached subsequently. Deeper sharing is possible since
the jump table depends on the task's code and not on its runtime status.
So this optimization makes jump tables be independent of the state_machine
object and stores them on the task function object itself, so multiple
invocations of task can all share the same jump table.