QmlJS: Try to implicitly import libraries in the same directory.

In QML, the current directory that holds a QML file is imported
implicitly. If it contains a qmldir file, the library is imported.

Since there is no explicit import statement, Creator can't know the URI
of this library. However, if type information is available for it
already - either through a previous dump or a qmltypes file - we can
guess the URI by looking at the contained exports.

Task-number: QTCREATORBUG-3768

src/libs/qmljs/qmljsinterpreter.h

@@ -982,6 +982,7 @@ public:
     enum Type {
         InvalidImport,
         ImplicitDirectoryImport,
+        ImplicitLibraryImport,
         LibraryImport,
         FileImport,
         DirectoryImport,