Refactore interfaces and reorganize files a bit
* Remove 'core' folder and reorganize root package structure
* Introduce interface's base class and implement 'api' and 'cli'
* Add a Package class and a moulinette initialization method
* Start to replace YunoHostError by MoulinetteError
* Fix actionsmap/yunohost.yml to follow extra parameters rules
Try to improve time execution and continue refactoring
* Revert to classes centralization into actionsmap.py
* Try to optimize conditions and loops
* Revisit Package class and get directories from a file generated at build
* Early refactoring of i18n
* Move yunohost library into /lib