Add linear support for QueryNode.fill

[SamuelToh]

Required for all non-trivial PRs

• Rebased/mergable
• Tests pass
• CHANGELOG.md updated
• Sign CLA (if not already signed)

Required only if applicable

You can erase any checkboxes below this note if they are not applicable to your Pull Request.

• TICKscript Spec updated

[SamuelToh]

@nathanielc Git noob here. So earlier on, at here you spoke about squashing all the commits and rebasing my fork.

Tried doing that, and since before my submission I actually did a bad move by syncing my fork repository by git merge instead of git rebase, so I thought I will just revert the merge first before rebasing again.

Reverted the merge and I did a rebase, somehow managed to get to a state where the commit log looks as thou I have just forked from the main repository. Good but it seems like Github had automatically closed my pull request, so I made a new one here... Hopefully this won't be an issue for you to merge.

[nathanielc]

@SamuelToh No worries. Not sure why github closed the other PR but this one will work. Can you update the changelog to reflect the new PR number? Then a simple rebase +squash should work since you have a nice commit history now.

Also in the future it is helpful to create a new branch on your fork of the repo so that you can sync with upstream and then rebase off the updated local master branch.

Example git workflow:

1. Fork repo and add upstream remote: git remote add upstream http://....`
2. Create new local branch git checkout -b <name of branch> master
3. Make changes
4. Sync with upstream git fetch upstream master:master
5. Rebase off updated master git rebase -i master
6. Push change and submit PR: git push

[SamuelToh]

@nathanielc I have squashed the commits. We should be all good now. Let me know if there is still problems.
Thanks for the git tips. I'll do that on my next pull request.

[SamuelToh]

@nathanielc Is this an intermittent issue? Because I had updated was CHANGELOG.md.

Test_Combination_Count, "failed with error: === RUN Test_Combination_Count".

[nathanielc]

@SamuelToh I reran the build and its green now. We have a few of those intermittent failures we are trying to track down.