Finally found and fixed that pesky "Could not pass event PlayerInteractEvent" error. Thanks to Gustavo_Player for a detailed stack trace that pointed me to the bug.
Built against Spigot 1.16 API.
Minor source code cleanups and encoding fixes.
Replaced mcstats with bstats.
Increased version to 2.0 to decouple it from Minecraft versions. EasyCarts 2.0 should work on basically any Spigot version, since it only uses basic API calls. I could only test EasyCarts 2.0 on Minecraft 1.16 though.
Note that this is not yet the big update that supports driving fast on diagonal rails. That will be EasyCarts 3.0 and it's still in the testing phase.