Concurrent Task refactor

[aconstlink]

In the wire library, I am currently implementing, it occurred to me that the task system can be used to connect nodes in the wire system for the execution part. So nodes will be called in parallel if required. Unfortunately, the task system needs some updates.

In the task there are inbetween tasks stored. This is not required anymore. We can just keep the outgoing tasks that follow in execution after the task.

In an inbetween is required, the currently following tasks can be reconnected.

A disconnect function is missing. A disconnect should disconnect the called tasks from its connected tasks. For this reason, a task requires in predecessors.

• [x] remove inbetweeners
• [x] implement disconnect
• [x] implement incoming/outgoing tasks

[aconstlink]

Issue is done so far. Although I removed the possibility to add tasks dynamically while the task is executed. I never really used that feature, so I dropped it.