Add <algorithm> include and remove explicit 3rdparty/GSL include reference

src/Base/PreCompiled.h

@@ -76,6 +76,7 @@
 #include <memory>
 #include <mutex>
 #include <bitset>
+#include <algorithm>
 
 // streams
 #include <iostream>

src/Base/Sequencer.cpp

@@ -26,6 +26,7 @@
 #ifndef _PreComp_
 #include <mutex>
 #include <vector>
+#include <algorithm>
 #endif
 
 #include "Sequencer.h"

src/Mod/Start/Gui/GeneralSettingsWidget.h

@@ -25,7 +25,7 @@
 #define FREECAD_START_GENERALSETTINGSWIDGET_H
 
 #include <QWidget>
-#include <3rdParty/GSL/include/gsl/pointers>
+#include <gsl/pointers>
 
 class QLabel;
 class QComboBox;

src/Mod/Start/Gui/ThemeSelectorWidget.cpp

@@ -31,7 +31,7 @@
 #endif
 
 #include "ThemeSelectorWidget.h"
-#include <3rdParty/GSL/include/gsl/pointers>
+#include <gsl/pointers>
 #include <App/Application.h>
 #include <Gui/Application.h>
 #include <Gui/PreferencePackManager.h>