List of feature to implement:

Edition of applications:
- constants: CRUD;
- components: xxxx ;
- links : xxxx, ordering
- invocations: xxUx, ordering
- sheets: xxxx
- process: xxxx, ordering (done)

Custom component edition widgets;

Components: read/save from a file;

Component placement in a sheet (using dot ?)

Refactor applicationview.h

Components: select with only one dialog box the list of availables ports.

Make evolve the engine API, especially sheets !

Unify some mecanisms :
    defaultPen and markForDeletion for sheet items.

Remove code replicates in GraphicsComponentItem
