src: clean white-spaces and license in some files

Signed-off-by: Jean Privat <jean@pryen.org>
src: create groups for related things

File are moved, some minimal change in importations

* modelize
* semantize
* frontend
* compiler
* interpreter

Signed-off-by: Jean Privat <jean@pryen.org>
contrib/online_ide: fix import of interpreter modules

Signed-off-by: Jean Privat <jean@pryen.org>