[Gui] Switch from boost::tuple to std::tuple

It's better to use the standard lib when possible

src/Gui/ExpressionCompleter.cpp

@@ -454,7 +454,6 @@ void ExpressionCompleter::slotUpdate(const QString & prefix, int pos)
 {
     init();
 
-    using namespace boost::tuples;
     std::string completionPrefix;
 
     // Compute start; if prefix starts with =, start parsing from offset 1.
@@ -469,7 +468,7 @@ void ExpressionCompleter::slotUpdate(const QString & prefix, int pos)
     std::string expression = Base::Tools::toStdString(prefix.mid(start));
 
     // Tokenize prefix
-    std::vector<boost::tuple<int, int, std::string> > tokens = ExpressionParser::tokenize(expression);
+    std::vector<std::tuple<int, int, std::string> > tokens = ExpressionParser::tokenize(expression);
 
     // No tokens
     if (tokens.size() == 0) {

src/Gui/PreCompiled.h

@@ -77,12 +77,12 @@
 #include <bitset>
 #include <unordered_set>
 #include <unordered_map>
+#include <tuple>
 
 // Boost
 #include <boost_signals2.hpp>
 #include <boost/bind/bind.hpp>
 #include <boost/program_options.hpp>
-#include <boost/tuple/tuple.hpp>
 #include <boost/utility.hpp>
 #include <boost_graph_adjacency_list.hpp>
 #include <boost/filesystem/path.hpp>