refactors problem handling to transform a bad null pointer exception in a clean ModelBuildingException when the source folder contains twice the same type
refactors the launcher and adds an option for the upcoming noclasspath option
slight change in the specification of an error case
adds support for spoon models without the complete classpath
adds support for spoon models without the complete classpath
merges conflict
Merge pull request #57 from monperrus/noclasspath

adds support for building the model of a program for which the classpath is incomplete