Merge: astbuilder: First implementation of clonable for ast nodes
## Astbuilder
- Now all the nodes of the ast is cloneable. Currently just a part of node have an implemented clone method.If we clone a node by default (not implemented) the program abort and print the following message: `The clone method is not implemented for ATestNode class.`. Currently the library is in **test** phase. You can have "maybe" some bug with the clone.
- Add a method to make the creation of a callsite easier.
## Futur work
Currently i am working on a test to make sure the result clone is the same as the original.
Pull-Request: #2779
Reviewed-by: Jean Privat <jean@pryen.org>