las3_pub / predictable_parallel_patterns

The lock was not released when an split_task was executed. We did a dirty fix by allowing the method to unlock the lock itself, but this has to be done cleaner in the future.

This means that high level tasks can be stolen and lays the groundwork for implementing different tasks like classic work stealing.

This will be used for storing thread tasks aligned in continous memory, allowing different theads to work on the data without interfearing.

Right now no work can be spawned, we simply have a proove of concept that we start up each thread, work for the master to finish and then synchronize back to the main thread.

See NOTES.md for details, basically std::thread can use dynamic memory allocation internaly and we want to prevent that.

The local storage per thread is only a pointer, this must be assigned AFTER the local storage object has moved to it's final location (e.g. on the stack of the caller). We might even change this a little further in the future to make the location of the state object more transparent.

The first draft of the internal threading component is currently only implemented using the c++11 std::thread, pthread support will be added next.