Don't exit early on finding a non-exported import (#1581).
Don't break encapsulation by letting outsiders change the internals of the Module
Don't add the language module as a dependency to itself (fixes #1581)
Added test for #1580
Added test for #1581
Improved test for #1469 somewhat
Removed unnecessary depedency on JUnit (#1469)
Added `com.redhat.ceylon.compiler.java.metadata` to the list of special rules for imports (#1469)
Changed return type of `instance()` because it's not impossible that returns a previously registered object of the wrong type (#1469)
Added new resolve error for missing Ceylon imports (#1469)
Now checking that imports from Java code inside Ceylon modules follow the rules set by Ceylon modularity (#1469)
Make sure the source language is set to Ceylon when entering the Ceylon trees (#1469)
Make sure that Ceylon compile tasks have their proper class path set just like we do in the CLI `Launcher` (#1469)
Don't throw an exception when encountering an ERROR type from within `convertNonPrimitiveTypeToDeclaration()` and let the caller handle it (#1469)
Added `getClassPathAsString()` to the Ceylon class loader and made the `Launcher` use that instead of having its own version (#1469)
Made `isImported()` public (#1469)
Made `lookupModuleInternal()` public and renamed it to `lookupModuleByPackageName()` (#1469)
Fixed tests that failed becuase of changes made for #1469
Fixed test for #1581 now that #1469 is fixed
Added `package.ceylon` for the #1469 test