ModuleMessagingExt v2.1d for Orbiter 2010 2018-06-24

(Minor tidy-up from previous major release - 2.1a re-adds in the compatibility files for old MM v1 MFDs, 2.1b minor bugfix, 2.1c better MMExtMFD, and tidied MMExt interface, v2.1d fixed bug in MMExtMFD PRV NXT with no data)
This is a major release of the Module Messaging Extended library: a utility that allows data sharing between any Orbiter module. Examples of data interchange: LaunchMFD to TransX, RV Orientation to BaseSync and Glideslope. For this release, the core has been rewritten fron scratch to eliminate startup dependency error 126 errors. The old interface has been preserved for existing MFDs that rely on it, but there is a new and much cleaner set of v2 interfaces to allow developers to share data with a minimum of just 3 lines of code. This version also has a MMExt2MFD interface into the core data handler, so you can see data exchange in real time in the simulation. There are no longer any pre-requisites (no run time dependencies, etc.)
Co-authored by Enjo and ADSWNJ.