Updates to the CMake modules.

  * Fixed a path resolution for Wintermute's core binary.
  * Moved a discovery for PkgConfig into the method, called when needed.
Updates to Factory and IPC.

  * Ensured that invalid UUIDs for plugins aren't loaded.
  * Stuck to using preprocesed defines for constant strings.
Refactored out some startup logic.

  * Lighten up the IPC::start() method.
  * Split the 'root' and 'plugin' flows into their respective singletons.
  * Defined Core::prepareAdaptor().
  * Defined Factory::prepareAdaptor().
  * Defined Factory::preparePluginAdaptor().