Create a task manager plugin with locking mechanism

[Gjum]

• Create a plugin for creating and managing multiple tasks using task.RunTask, as this is only a helper class and should not be exposed this way.
• Should provide ways to prevent multiple tasks to interfere, for example two tasks at the same time moving into opposite directions or using the inventory by clicking slots or blocks.

See also:

• discussion on Combining multiple tasks PrismarineJS/mineflayer#275, especially the scheduling part
• some example tasks

[Gjum]

This is not completely done:

Should provide ways to prevent multiple tasks to interfere, for example two tasks at the same time moving into opposite directions or using the inventory by clicking slots or blocks.