Introduce SimulationTime config

Use SimulationTime to forcefully stop simulation at a specified point in
time.

configs/README.md

@@ -157,6 +157,7 @@ The content of [ddr3.json](simconfig/example.json) is presented below as an exam
 {
     "simconfig": {
         "SimulationName": "example",
+        "SimulationTime": 1e-3,
         "Debug": false,
         "DatabaseRecording": true,
         "PowerAnalysis": false,
@@ -173,6 +174,9 @@ The content of [ddr3.json](simconfig/example.json) is presented below as an exam
 
 - *SimulationName* (string)
     - Give the name of the simulation for distinguishing from other simulations.
+- *SimulationTime* (double)
+    - Time at which the simulation is forcefully stopped. Useful for generating multiple simulations over the exact same timeframe.
+    - Default: unlimited
 - *Debug* (boolean)
     - true: enables debug output on console (only supported by a debug build)
     - false: disables debug output