- FutureIU can now use an existing InputBuffer

[.. code ...]
IPAACA_SIMPLE_TIMER_BEGIN(blockid1)
[... first code block to time ...]
IPAACA_SIMPLE_TIMER_END(blockid1, "Processing loop 1")
[...]

-> e.g.: "Processing loop - us elapsed: 15" to terminal

Several blocks can be timed in one stack frame using more blockids
(TODO: implement profiling mode that can be turned on/off)

Disabled removal of retracted IUs from InputBuffer to
match the Python version - since it is an item of discussion
that will be resolved in the next version anyway.

They are torn down on program exit (retracting all live IUs)

- OutputBuffer retracts all remaining live IUs on destruction
- sends correct event type now
- fixed reference error for calling handlers
- setters properly check for retracted flag
- also added some missing checks for committed flag

* Exceptions when trying to modify retracted IUs.
* Removal of IU also retracts it.

- OutputBuffer retracts all remaining live IUs on destruction
- sends correct event type now
- fixed reference error for calling handlers
- setters properly check for retracted flag
- also added some missing checks for committed flag

* Filtering by IU event type.
* Description of sniffer arguments after startup now prettier.

Also removed stray cout lines