Automatically calculate total number of plants and seeds

[Samuel-Therrien-Beslogic]

• [x] The project passes automated tests (build, linting, etc.).
• [x] You updated the project's documentation with new changes.
• [x] You've linked any issue this PR closes
• [ ] You reviewed your own PR and made sure there's no test/debug code or any obvious mistakes.

Make sure that the code wasn't copied from elsewhere (check one):

• [x] This is your own original code
• [ ] You have made sure that we have permission to use the copied code and that we follow its licensing

Closes #241