Added Loading World state

Author: ayushgnv

msg/SimulationState.msg

@@ -1,18 +1,24 @@
 # Simulation states used in SetSimulationState and returned in GetSimulationState
 
-uint8 STATE_STOPPED      = 0           # Simulation is stopped, which is equivalent to pausing and resetting with ALL.
-                                       # This is typically the default state when simulator is launched.
-                                       # Stopped simulation can be played. It can also be paused, which means
-                                       # starting simulation in a paused state immediately,
-                                       # without any time steps for physics or simulated clock ticks.
-uint8 STATE_PLAYING      = 1           # Simulation is playing, can be either paused or stopped.
-uint8 STATE_PAUSED       = 2           # Simulation is paused, can be either stopped (which will reset it) or played.
-uint8 STATE_QUITTING     = 3           # Closing the simulator application. Switching from STATE_PLAYING or STATE_PAUSED
-                                       # states is expected to stop the simulation first, and then exit.
-                                       # Simulation interfaces will become unavailable after quitting.
-                                       # Running simulation application is outside of the simulation interfaces as
-                                       # there is no service to handle the call when the simulator is not up.
+uint8 STATE_STOPPED          = 0           # Simulation is stopped, which is equivalent to pausing and resetting with ALL_PAUSED.
+                                           # This is typically the default state when simulator is launched.
+                                           # Stopped simulation can be played. It can also be paused, which means
+                                           # starting simulation in a paused state immediately,
+                                           # without any time steps for physics or simulated clock ticks.
 
-uint8 STATE_NO_WORLD     = 4           # Simulation world is currently unloaded, and/or a new world has not finished loading yet.
-                                       # The simulation is inactive and cannot be started, stopped, or paused.
+uint8 STATE_PLAYING          = 1           # Simulation is playing, can be either paused or stopped.
+
+uint8 STATE_PAUSED           = 2           # Simulation is paused, can be either stopped (which will reset it) or played.
+
+uint8 STATE_QUITTING         = 3           # Closing the simulator application. Switching from STATE_PLAYING or STATE_PAUSED
+                                           # states is expected to stop the simulation first, and then exit.
+                                           # Simulation interfaces will become unavailable after quitting.
+                                           # Running simulation application is outside of the simulation interfaces as
+                                           # there is no service to handle the call when the simulator is not up.
+
+uint8 STATE_NO_WORLD         = 4           # Simulation world is currently unloaded.
+                                           # The simulation is inactive and cannot be started, stopped, or paused.
+
+uint8 STATE_LOADING_WORLD    = 5           # Simulation world is currently loading.
+                                           # The simulation is inactive while world is loading and cannot be started, stopped, or paused.
 uint8 state