Provide inline assembly to the code generator. (#840)

* Directly usable inline assembly.

* Add missing header.

libsolidity/codegen/ExpressionCompiler.cpp

@@ -23,6 +23,7 @@
 #include <utility>
 #include <numeric>
 #include <boost/range/adaptor/reversed.hpp>
+#include <boost/algorithm/string/replace.hpp>
 #include <libdevcore/Common.h>
 #include <libdevcore/SHA3.h>
 #include <libsolidity/ast/AST.h>