- Rename OP_SUBSTR to OP_SPLIT
- Add OP_BIN2NUM & OP_NUM2BIN, replacing OP_LEFT and OP_RIGHT
- tests in script_tests.json were updated to use the renamed opcodes
- Also added FIRST_UNDEFINED_OP_VALUE, the first value of undefined opcodes - OP_NOP10+1 was being used for this purpose which is confusing
Author: Joshua Yabut
Co-author: Daniel Connolly