Introduce UndoList with a redoList to keep track of redo
line add and delete. undo and redo not fixed yet
Undo-redo works for create
commit
Undo works - Phase 1 - Undo for create work!
Undo and Redo works - Phase 2 - both create and delete
Undo and Redo works - Phase 3 - Update works
Major change

1. Rectify all undo - redo functions - Create, delete, update, and
complete
2. Package all logic class - Command class and all the children can be
called by importing the logic package
3. Change IndigoLogic name to Logic Facade.
Solve conflicts to merge Undo-redo branch and master
Merge branch 'master' of https://github.com/cs2103aug2014-t11-4j/main