[#13] fix integration test for mapper with mapper from other package

the integration test was actually written with the dedicated class from another package as a dependency, not the interface generated from it
test was therefor actually useless for the test case it was supposed to cover
[#6] find unresolved types in source class elements not used by DAMapping

in previous implementation, unrevolved type references were identified only in elements of the source class (variables, methods, ...) which were actually used by DAMapping
for example, a variable or property with an unresolved reference did not stop DAMapping from generating interfaces/classes even though the source class would never compile
for the time beeing, the same resolution strategy is used: find references to generated code by simpleName only
[#13] move tests for references to generated code to specific module
[#13] add integration test for 4 elements dedicated class chain