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

* Refactoring applied mostly because we need to satisfy the new state
  of GenericProcessor after refactoring;
* Also there were a lot of stylystic fixes applied, some minor
  improvements using C++11.

Created Xcode projects for all currently-built plugins.  Added Xcode workspace with "All" scheme for building GUI and all plugins.  Addressed some compiler warnings in plugin code.

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

added functions to network module to retrieve acquisition/recording status and the current recording path