Issue-423: Crash when editing device dataitem in DeviceModel

[mnoomnoo]

#423

Updated Checkpoint::updateDataItems() to remove orphans from observations map. Updated CircularBuffer::updateDataItems() to remove orphans from m_slidingBuffer

[wsobel]

We can't erase from the circular buffer since the positions are computed using the sequence numbers. it is better to leave holes. When we get observations from the circular buffer, it skips orphaned observations. The checkpoint code looks correct.

Did you write a test to verify the changes?

[mnoomnoo]

I updated CircularBuffer::updateDataItems() to skip orphaned dataItems instead of deleting them from the sliding buffer. Checkpoint::updateDataItems() still deletes orphaned observations.

Did you write a test to verify the changes?

I didn't write a test to verify the changes. I can take a peek at existing unit tests to see if there is something I can modify to test the agent when data items are added / removed or their IDs are changed.

[wsobel]

Thanks a lot. I will review changes later today. - W