Fixed compiler warnings.

src/modes/world.cpp

@@ -459,7 +459,7 @@ void World::terminateRace()
     {
         std::string mode_name = getIdent(); // Get the race mode name
         int winner_position = 1;
-        int opponents = achiev->getInfo()->getGoalValue("opponents"); // Get the required opponents number
+        unsigned int opponents = achiev->getInfo()->getGoalValue("opponents"); // Get the required opponents number
         if (mode_name == IDENT_FTL)
         {
             winner_position = 2;

src/states_screens/dialogs/enter_gp_name_dialog.cpp

@@ -84,7 +84,7 @@ void EnterGPNameDialog::onEnterPressedInternal()
     if (name.size() > 0)
     {
         // check for duplicate names
-        for (int i = 0; i < grand_prix_manager->getNumberOfGrandPrix(); i++)
+        for (unsigned int i = 0; i < grand_prix_manager->getNumberOfGrandPrix(); i++)
         {
             const GrandPrixData* gp = grand_prix_manager->getGrandPrix(i);
             if (gp->getName() == name)

src/states_screens/edit_gp_screen.cpp

@@ -199,7 +199,7 @@ void EditGPScreen::onConfirm()
     if (m_action == "remove")
     {
         m_gp->remove(m_selected);
-        setSelected(m_selected >= m_gp->getNumberOfTracks() ?
+        setSelected(m_selected >= (int)m_gp->getNumberOfTracks() ?
             m_gp->getNumberOfTracks() - 1 : m_selected);
         loadList(m_selected);
         setModified(true);