* For original and binary recording engines
* This allows the messages file to be viewed in a text editor

Ensure that plugin entry points are always exported on macOS and Linux (otherwise, plugins won't load in macOS release builds)

* Refactoring and stylystic fixes of RecordEngine class (and one
  dependency).
* Refactoring and stylystic fixes of DataThread class and all
  appropriate dependent classes.

Fixed: Changing data directory in GUI did not take effect if a recording had been started (and stopped) before. Only the first directory before the first recording was used. Fixed: EventBroadcaster was linking to Debug version of open-ephys.lib in Release mode

added functions getRecordingNumber and getExperimentNumber to CoreServcies. Extended NetworkEvents plugin to send this upon request

Fixed: Changing data directory in GUI did not take effect if a recording had been started (and stopped) before. Only the first directory before the first recording was used. Fixed: EventBroadcaster was linking to Debug version of open-ephys.lib in Release mode