Several improvements:
- task_create_ex, not it takes a parameter structure which can be easily
  initialized. Example in examples/ball.c and test/task_create.c. The
  old task_create() is still available

- Possibility to select the initial activation pattern. By default, the
  thread blocks on the internal semaphore and the task_create activates
  it. However, it is possible to avoid direct activation, and to avoid
  implicit blocking by modifying the creation parameters

- tstat.h provides ways to measure the wcet and average execution times
  of tasks. An example in examples/ball.c

- Added support for processor allocation. Now it is possible to
  allocate a thread on a single processor.