Made Log Error/Warning recording thread-safe

The MessageLogger has the ability to record the LogError and LogWarning messages which can then be gathered by user code. This was changed to be thread safe by collecting the messages per Stream in a thread safe map and then having the system clear those maps once the Stream has finished with an Event. Although this is a behavior change, the only way this feature was used in the past was to gather the messages per Event anyway.
Added missing includes
Use LoggedErrorsSummary functions rather than the global variables

All global variables associated with Logging of the MessageLogger error
messages have been made private since they were changed to be thread-safe.
This code has been changed to use the public functions instead.
Merge pull request #1566 from Dr15Jones/makeErrorSummaryLoggingThreadSafe

Multithreading fixes -- Made Log Error/Warning recording thread-safe.