#7 Conjugation application

[Olivier Jacquemin]

Add a second application.

Extend the program to propose a second application: conjugation of "avoir" and "être" in the present tense.

This application is sufficiently different from the first one (multiplication tables) to be able to separate the framework from the applications.

The interface(s) between them should be better defined after this step. Adding a third application afterward should involve much fewer changes to the framework.