This pull request contains a the same implementation of OP_CHECKTEMPLATEVERIFY (BIP119) as @jamesob’s Covenant Tools, an implementation of OP_CHECKSIGFROMSTACK(VERIFY) and of OP_INTERNALKEY.
There are no testnet or mainnet activation parameters proposed in this pull request. I am deeply uninterested in the details of activation semantics.
This combination of changes allows for the implementation of a variety of layer two proposals and improvements. Including, but not limited to, Lightning Symmetry, Point-Time-Locked-Contracts, Timeout Trees, and unidirectional non-interactive channels.
For anyone interested, I also have a branch with these same changes based on the latest release.