las3_pub / predictable_parallel_patterns

It is now possible to use a memory mapped stack that throws a SIGSEV if thes coroutine stacks are exhausted.

The rationale to do an custom implementation is that the existing solutions are quite a bit slower and/or require more memory.

We implement a minimal concepts of user level threads. This shows the minimum requirements for our 'staggered' stack implementation: we need to be able to switch to a new stack and allow someone else to continue the calling function right before the switch.

We changed how the memory is allocated from passing char* buffers to then store objects into to creating 'fat objects' for all scheduler state. This eases development for us, as we can make changes to data structures without too much effort (e.g. add a second array to manage tasks if required).

The __thread implementation of thread local, static variables seems more efficient, so we activate this by default. If it is (for some reason) not available/slower than the pthread version, one can toggle it for the specific system/processor later on using macros.

There are serval ways we could optimize the calls, but for now this should be enough for first tests.

We force linker errors if the new operator is used somewhere. See NOTES.md for details.

Seperate library from other parts of project (samples, playground, testing, ...). We still are in one 'toplevel' cmake project, so we can for exmaple compile everything (library and playground) in debug mode, for simple development.