Add the ability to schedule scripts based on wallclock time (closes #1773)

include/openspace/scripting/scriptengine.h

@@ -115,6 +115,8 @@ public:
         double timeout, std::string preScript = "", std::string postScript = "");
     void removeRepeatedScript(std::string_view identifier);
 
+    void scheduleScript(std::string script, double delay);
+
     std::vector<std::string> allLuaFunctions() const;
     const std::vector<LuaLibrary>& allLuaLibraries() const;
 
@@ -158,6 +160,15 @@ private:
     };
     std::vector<RepeatedScriptInfo> _repeatedScripts;
 
+    struct ScheduledScriptInfo {
+        // The script that should be executed
+        std::string script;
+
+        // The application timestamp at which time the script should be executed
+        double timestamp = 0.0;
+    };
+    std::vector<ScheduledScriptInfo> _scheduledScripts;
+
     // Logging variables
     bool _logFileExists = false;
     bool _logScripts = true;