Add slicing and dependency through cmd line

[XiangyuG]

Now, we can add more parameters through cmd line to specify the input packet fields and our spec assert for slicing.

[taegyunkim]

Few things to check

1. Appveyor is not run for this branch
2. Adding this to chipmunk makes this repo diverge from chipmunk-tofino, I think cherry picking commits in chipmunk-tofino should be done first.

@anirudhSK What do you think?

1. In your local git repo, add remote chipmunk-tofino
2. git fetch
3. for each new and meaningful commit in the chipmunk-tofino repo,
   • git cherry-pick --no-commit
   • remove tofino related files/code snippets
   • test
   • Write meaningful commit message
   • commit

Or

1. In your local git repo, add remote chipmunk-tofino
2. git fetch
3. git diff <chipmunk-tofino/master> chipmunk/master > diff.patch
4. Apply and remove tofino related code

Cherry-picking commits from chipmunk-tofino should be done in separate PR(s).

[taegyunkim]

I don't know how you generated those so many "Merge branch 'master' of https://github.com/chipmunk-project/chipmunk" commits with zero diffs, consider dropping them using https://stackoverflow.com/a/1338758.

For the last commit, 26659ed, update the commit message appropriately. $> git commit --amend

[anirudhSK]

@taegyunkim: Thanks for noticing that the AppVeyor build wasn't running. I tried getting AppVeyor to work a few times, but I think some configuration setting (either on GitHub or AppVeyor) is causing AppVeyor builds to not be triggered.

GitHub Actions might be a better choice (#195) because it involves much less cross-app configuration and authentication.

About the merge commits, let's let them be. Eventually, it all turns into one single commit on master anyway. It's more important that that single commit is readable and passes tests.

About cherry-picking commits from the other repo, let's figure out how to do it most efficiently when we next meet.

@XiangyuG: Once we merge #195, let's redo the current PR on top of the new master.