Made PropertySet::setValue() methods take a StringRef instead of a const String& so that Identifiers can be implicitly cast

VST3:  Unload macOS bundle in destructor of DLLHandle with CFBundleUnloadExecutable() to fix crash when loading some third-party plug-ins a second time

macOS:  Added NSAppleEventsUsageDescription plist key to the AudioPluginHost to fix instantiating some third-party plug-ins

Projucer:  Added a setting for enabling and setting the macOS NSAppleEventsUsageDescription plist key

Deprecated AffineTransform::getScaleFactor() as it was producing incorrect values for transforms containing rotations. Added getDeterminant() method for getting the determinant of the transform

macOS:  Fixed another spurious dynamic_cast type_info warning when loading dylibs containing JUCE at runtime

WASAPI:  Suspend processing when AudioSessionStateInactive session event is received and restart on AudioSessionStateActive

Linux:  Revert c47c790f and instead defer modifications to the fdReadCallbacks vector when inside a read callback until after the callback has been executed