v1.08

• Timers API changed: now, timer callback TN_TimerFunc is called
  with global interrupts enabled.
• Fix for pic24/dspic: previously, initial value of PSVPAG for new tasks
  was always 0, but it is not necessarily the case. This might cause troubles
  with constants in program space. Now, when initializing stack for new task,
  current value of PSVPAG is used.
• Fixed round robin:
  • Even though the tasks were flipped in the runnable tasks queue, the
    actual context switch wasn't performed;
  • Tasks were switched with a requested period + 1 tick.
• Added an option TN_FORCED_INLINE
• Added an option TN_MAX_INLINE