Uses breadth-first node walking in TypeAnalyzer::basicRun()

For correct inference of the parallel paths in a graph
it is critical to perform traverse breadth-first.

Otherwise, phi nodes may have their incomings undefined.

Issue: #17
Issue: #92

src/TypeAnalyzer.cpp

@@ -168,7 +168,7 @@ void TypeAnalyzer::fillLinkerClosures() {
 
 bool TypeAnalyzer::basicRun() {
     m_walker.resetStopNodes();
-    m_walker.run(*m_graph.nodes_begin(), Walker::wdForward, GraphWalker::wtDepthFirst, true);
+    m_walker.run(*m_graph.nodes_begin(), Walker::wdForward, GraphWalker::wtBreadthFirst, true);
 
     return m_context.getRawReturnType().getSubTypes().size() == 1;
 }