Add more flexibility to construction of Time instances

include/openspace/util/time.h

@@ -58,7 +58,7 @@ class SyncBuffer;
 
 class Time {
 public:
-    Time();
+    Time(double secondsJ2000 = -1);
     Time(const Time& other);
 
 
@@ -77,6 +77,8 @@ public:
      */
     static void deinitialize();
 
+    static Time now();
+
     /**
      * Returns the reference to the Time singleton object.
      * \return The reference to the Time singleton object
@@ -120,6 +122,8 @@ public:
      */
     double currentTime() const;
 
+    double unsyncedJ2000Seconds() const;
+
     /**
      * Returns the current time as a formatted date string compliant with ISO 8601 and
      * thus also compliant with the Spice library.