More work.

- Moving DeleteSubsequence out into ByteTwiddling, and renaming it to
the more appropriate "DeleteAllOccurrencesOfSubsequence".
- Re-implementing DeleteAllOccurrencesOfSubsequence using
Knuth-Morris-Pratt.
- Adding a test class for ByteTwiddling, and moving the tests for
DeleteSubsequence there.
- Adding tests for the NOP family of opcodes.
- Changing unnecessarily wide "size types" in transaction script runner
to just "int".  It's just not worth it...