* Implement syscalls for BYTE, SIGNEXTEND, SAR, SLT and SGT.
* Implement SDIV and SMOD; minor documentation and tidying.
* Implement EXP.
* Add sys_byte to the syscall jumptable.
* Test suite for signed syscalls.
* Handle `EXIT_KERNEL` "properly".
* Add gas charges; rename label.
* Uppercase all opcodes.
* Add test for BYTE; fix bug in BYTE.
* Calculate and charge gas for calling `EXP`.
* Fix gas calculation for `exponent = 0`.
* Address Jacqui's comments.
* Remove BYTE syscall as it will be implemented natively.
* Oops, forgot to remove this bit.
* windowed mul
* Working
* Window of 4 bits
* Fix
* Comments
* Unroll loop
* Unroll loop
* remove global
* Minor
* Minor
* Implement `CALLVALUE, CALLDATALOAD, CALLDATASIZE, CALLDATACOPY` in interpreter
* Minor
* Doesn't work
* Minor
* Minor
* wnaf msm
* Working hardcoded values: 28657 opcodes
* Working wnaf
* Small wnaf optim
* Precompute works
* Working together
* Bump to 129 bits
* Working glv decomposition
* Working MSM with GLV
* Almost working
* Working
* ECC test folder
* Working with real sig data
* Fix tests + Clippy
* Minor
* Cleaning
* Comments
* Cleaning
* Smaller glv test file
* Print opcode count at the end of interpreter run
* More constants
* Add z3 proof that the GLV scalars are 129-bit or less
* Minor change to z3 proof
* Minor
* Hamish's suggestion
* Working
* Cleaning
* Clippy
* PR feedback
* Minor PR feedback
I made a couple related changes to `Interpreter`:
- Only enforce the `JUMPDEST` rule if we're in kernel mode.
- Convenience methods for dealing with the RLP and txn field segments of memory.
