FORMUS3IC_LAS3 / embb

A blocking binary heap based priority queue for tasks with deadlines has been
added. The priority queue sorts incoming tasks according to their
increasing deadline attribute.

This commit adds the deadline attribute to the task attributes struct.
The task deadline is an 64bit value.

On releasing all resources, the node waits for the completion of all
tasks which are associated to a specific action. Since we never
incremented the task counter for actions, this loop spun.

The cmake configuration option HARD_REALTIME was added. This sets or
unsets the compile time variable EMBB_HARD_REALTIME.

# Conflicts:
#	README.md

Merge branch 'embb517_mutex_based_atomics' of https://github.com/siemens/embb into embb517_mutex_based_atomics

mtapi_c: fixed handling of detached tasks in conjunction with retaining queues and multi-instance tasks

# Conflicts:
#	mtapi_cpp/include/embb/mtapi/action.h
#	mtapi_cpp/include/embb/mtapi/group.h
#	mtapi_cpp/include/embb/mtapi/node.h
#	mtapi_cpp/include/embb/mtapi/queue.h
#	mtapi_cpp/include/embb/mtapi/task_attributes.h