v2.2.0

Changes & improvements:

• Thread recycling now stores multiple threads, and dynamically adjusts to the signals' need.
• When a reusable thread is created, it is now immediately used.
• Will no longer error if you attempt to disconnect a signal that isn't connected.
• Switched a task.spawn() to coroutine.resume.
• Cached coroutine.create and table.insert.
• Minor comment changes and additions.
• Renamed a few functions.