Added command to change the EnvironmentType

@Environment.SetEnvironmentType(ID)

This command temporarily sets the "EnvironmentType" parameter of the current map until a map change, which also changes the sky texture and sometimes adds particles. Value can be 0-5.
0 = Outside
1 = Inside
2 = Cave
3 = Dark (also makes all entities darker)
4 = Underwater (adds air bubble particles)
5= Forest

P3D/World/ActionScript/V2/ScriptCommands/DoEnvironment.vb

@@ -62,6 +62,11 @@
                         Screen.Level.DayTime = World.GetTime + 1
                     End If
                     IsReady = True
+                Case "setenvironmenttype"
+                    Dim newtype As Integer = int(argument)
+                    If newtype >= 0 AndAlso newtype <= 5 Then
+                        Screen.Level.EnvironmentType = newtype
+                    End If
             End Select
 
             Screen.Level.World.Initialize(Screen.Level.EnvironmentType, Screen.Level.WeatherType)

P3D/World/ActionScript/V2/ScriptLibrary.vb

@@ -427,6 +427,7 @@ Namespace ScriptVersion2
             r(New ScriptCommand("environment", "setrenderdistance", {New ScriptArgument("distance", ScriptArgument.ArgumentTypes.Str, {"0-4", "tiny", "small", "normal", "far", "extreme"})}.ToList(), "Sets the render distance."))
             r(New ScriptCommand("environment", "toggledarkness", "Toggles the ""IsDark"" parameter of the current map."))
             r(New ScriptCommand("environment", "setdaytime", {New ScriptArgument("daytime", ScriptArgument.ArgumentTypes.Int)}.ToList(), "Sets the daytime to use for the Outside EnvironmentType (0). Can be 1-4, any other number resets to the default daytime."))
+            r(New ScriptCommand("environment", "setenvironmenttype", {New ScriptArgument("environmenttype", ScriptArgument.ArgumentTypes.Int)}.ToList(), "Sets the ""EnvironmentType"" parameter of the map, which also changes the sky texture and sometimes adds particles. Value can be 0-5."))
             ' Constructs:
             r(New ScriptCommand("environment", "daytime", "str", "Returns the current DayTime of the game.", ",", True))
             r(New ScriptCommand("environment", "daytimeID", "int", "Returns the current DayTimeID of the game.", ",", True))