Groundwork. Prepare for automatic tagging

[Not compilable until the next commit]

libsolidity/analysis/ConstantEvaluator.cpp

@@ -29,6 +29,7 @@
 using namespace std;
 using namespace solidity;
 using namespace solidity::frontend;
+using namespace solidity::langutil;
 
 void ConstantEvaluator::endVisit(UnaryOperation const& _operation)
 {

libsolidity/analysis/ImmutableValidator.cpp

@@ -22,6 +22,7 @@
 #include <boost/range/adaptor/reversed.hpp>
 
 using namespace solidity::frontend;
+using namespace solidity::langutil;
 
 void ImmutableValidator::analyze()
 {

libsolidity/analysis/SyntaxChecker.cpp

@@ -123,7 +123,7 @@ bool SyntaxChecker::visit(PragmaDirective const& _pragma)
 			m_errorReporter.syntaxError(
 				_pragma.location(),
 				"Source file requires different compiler version (current compiler is " +
-				string(VersionString) + " - note that nightly builds are considered to be "
+				string(VersionString) + ") - note that nightly builds are considered to be "
 				"strictly less than the released version"
 			);
 		m_versionPragmaFound = true;