closes#5645
the code for this is borrowed from ItemEntity. I didn't feel like a base class was appropriate, and we can't (yet) declare constants in traits.
Fixes#4589
The following API methods are added:
- `XpManager->canAttractXpOrbs()`
- `XpManager->setCanAttractXpOrbs()`
Possible future scope: flip this on its head to allow spectator players to attract XP orbs, in case someone wants that for some reason ???
Co-authored-by: Dylan K. Taylor <dktapps@pmmp.io>
in pretty much every case, these usages really wanted to read the tag's contents anyway, which can be combined with a getTag() and instanceof call for more concise and static analysis friendly code.
In the few cases where the tag contents wasn't needed, it still wanted to check the type, which, again, can be done in a more static analysis friendly way by just using getTag() and instanceof.
this reduces the temptation to use it in high-level code, as well as making syncNetworkData() more useful (now it can export to many data collections, which means we can start to think about having a property cache per network session, which is more flexible)
