Introduce namespace langutil in liblangutil directory.

Also:
- Use {}-style list initialisation for SourceLocation construction
- Introduce new system includes
- Changes the API of the Scanner to take source as value (with move) as opposed to as a reference

libevmasm/ControlFlowGraph.cpp

@@ -275,7 +275,7 @@ void ControlFlowGraph::gatherKnowledge()
 			//@todo in the case of JUMPI, add knowledge about the condition to the state
 			// (for both values of the condition)
 			set<u256> tags = state->tagsInExpression(
-				state->stackElement(state->stackHeight(), SourceLocation())
+				state->stackElement(state->stackHeight(), langutil::SourceLocation{})
 			);
 			state->feedItem(m_items.at(pc++));