* Remove InternalsVisibleTo from Core to XF.Platforms.*
* Changes per Jason's code review
* Move LockableObservableListWrapper to internals namespace
* Changes per Stephane's code review
* update docs
* Touch code to get CI to run tests
* Rebase; Update documentation
* Repro
* Make messaging center callbacks weak references
* Preserve attribute
* Fix test method name
* Watch for collection of actual delegate target instead of wrapper delegate
* Preserve the original platform instance when changing main page
* Better tests for lambda situations
* Update tests, make callback target a weakreference if it's the subscriber
* Ensure old Platform MessagingCenter subs are gone before creating new Platform
kingces95
E.Z. Hart
adrianknight89
Rui Marinho
Jason Smith