Compare line page

[nmqng]

Description

The purpose of this pull request is to add a comparison line graphic page based on the design doc.

Fixes #953

Type of change

• Note merging this changes the database configuration.
• This change requires a documentation update

Checklist

• I have followed the OED pull request ideas
• I have removed text in ( ) from the issue request
• You acknowledge that every person contributing to this work has signed the OED Contributing License Agreement and each author is listed in the Description section.

Limitations

Currently, when a shifting to/from a leap year from/to a non-leap year, a warning show up to tell the user that the original graph and the shifted graph will not align appropriately. However, in the future, we would want to find a way that can make the two graphs align.

[huss]

I want to thank @nmqng for taking on this larger issue. I also ask your understanding for how long my review took as my efforts where focused elsewhere.

Overall, this does what the design document requested. I have made a number of comments to consider. In the big picture, I spent time considering how compare line functioned. In the end, based on your efforts, I concluded that changes in the logic were desired. This is due to my having a better understanding of the possibilities and not direct issues with your code. As a result, I have updated the design document with a new updated section to reflect my current thinking. I think the changes may simplify the code. I know you put in a lot of effort to get several of the current ideas implemented and I'm sorry for the changes. I also welcome your thoughts on what I wrote. If you want me to be actively involved in updating the code then please let me know.