Add `BlockController::getUniqueIdentifier()`
Add `BlockController::getUniqueIdentifier()`

Add `BlockController::getUniqueIdentifier()`

`BlockController::getIdentifer()` returns the same result for a block
and a clipboard block that contains a reference to that block. This is
awkward for javascript and other things where you need a unique
identifier for a block

matt9mg/concrete5,matt9mg/concrete5,matt9mg/concrete5,avdevs/concrete5,MichaelMaar/concrete5,MichaelMaar/concrete5,TimDix/concrete5,avdevs/concrete5,MichaelMaar/concrete5,TimDix/concrete5,TimDix/concrete5,avdevs/concrete5