Create backlog
  - [X] Move src/*.el files to /org-trello
  - [X] Add 'provide statements for each of those files
  - [X] Rework header + org-trello + footer files
  - [X] Adapt main org-trello.el files to reference the needed namespaces
  - [X] Adapt test files so that it continues to work (add the needed require statements)
  - [X] Adapt loading code routine for developing + testing
  - [X] Refactoring step - rename some files to avoid confusion
  - [X] Adapt README-dev.md to the current code adaptation
Update todo
Refactor - Adapt missing information.
Refactor - Remove useless namespaces (cf. trace-function)
  - [X] Adapt cask packaging
Add a target to compile org-trello.
  - [X] Add missing standard header to namespace
  - [X] Does org-trello still compiles? NO
  - [X] Fix simple compilation warnings
  - [X] Fix some more warnings
Fix - Use car/cdr implementation instead of first/second
Refactor - Move a function to its rightful namespace