Kudos to the Forge team for adding 4096 Support!
In the changelog on the github you state that you've based it off of Mdiyo's work. Does that mean that ID 0-255 are blocks, and 256-4095 can be both blocks and items? If that's the case, do you change the vanilla ID's to something >4096 or do they remain in place?
@ScottKillen: RP2's ID-code and IDResolver are indeed incompatible. If you have both, you need (from experience) to edit every ID manually to make it work. Otherwise several items will be allocated to the same ID, and several blocks as well (also using Mdiyo's fix (4.2), IDresolver and Forge .97)