few improvements for Custom/Local types: 
getDeclaredType check in getDirectChildren
a IRIValueType now gets a ReferenceLocation to know if it is
compatible/assignable to another (by just checking if it is the same
location)
support for "scopes.myscope.MyObject" also because of the assignable
check we now know if "MyObject" in one file is the same as
"scopes.myscope.MyObject"