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>

diff --combined tests/niti.skip
index 4beb4fb,fbcd87b..6e60c30
--- 1/tests/niti.skip
--- 2/tests/niti.skip
+++ b/tests/niti.skip
@@@ -5,7 -5,6 +5,7 @@@ nit_args
  nit_args5
  nit_args6
  nit_args8
 +nit_args9
  nitvm_args1
  nitvm_args3
  nitin
@@@ -46,3 -45,4 +46,4 @@@ test_cs
  repeating_key_xor_solve
  nitpm
  nitdoc
+ test_astbuilder

diff --combined tests/nitvm.skip
index 097ca87,232536b..61f68f8
--- 1/tests/nitvm.skip
--- 2/tests/nitvm.skip
+++ b/tests/nitvm.skip
@@@ -5,7 -5,6 +5,7 @@@ nit_args
  nit_args5
  nit_args6
  nit_args8
 +nit_args9
  nitvm_args1
  nitvm_args3
  nitin
@@@ -49,3 -48,4 +49,4 @@@ base_notnull_lit_alt
  assertions
  nitpm
  nitdoc
+ test_astbuilder