* When the cause of destruction was world-induced (CanBeAt check failed) there is no tool. Pass the nullptr directly to ConvertToPickups and let it handle it.
* Fixes#4795
- Remove unused a_Digger parameter to ConvertToPickups.
* BlockHandler initialisation is a constant expression
If we can't make it all namespaces, this is the next best I guess.
+ Tag handlers constexpr, const as needed
+ Inherit constructors
* Privatise handler functions
* More constexpr
Co-authored-by: Alexander Harkness <me@bearbin.net>