Separated lists and separated items (#247)

* trying out having the expressions and conditions of control structures

* adding the pattern for separated item and separated list

* adding documentation for the new functions

* Update src/nodes/print-separated-list.js

* add scripts to .travis.yml

* undo

* add package-lock.json

Co-authored-by: Franco Victorio <victorio.franco@gmail.com>
Co-authored-by: mattia richetto <mattia.richetto@gmail.com>

Author: 3 people

.gitignore

@@ -62,6 +62,6 @@ typings/
 
 .DS_Store
 
-package-lock.json
+# package-lock.json
 
 yarn.lock