C++ namespace cleanup (except tests).

libsolidity/analysis/ControlFlowAnalyzer.h

@@ -20,9 +20,7 @@
 #include <libsolidity/analysis/ControlFlowGraph.h>
 #include <set>
 
-namespace dev
-{
-namespace solidity
+namespace solidity::frontend
 {
 
 class ControlFlowAnalyzer: private ASTConstVisitor
@@ -47,4 +45,3 @@ private:
 };
 
 }
-}