Move software renderer into its own namespace to isolate its globals and make

any access explicit. This reveals the places in the code where they are being
accessed where they shouldn't and prevents accidental usage.

src/r_3dfloors.cpp

@@ -15,6 +15,11 @@
 #include "c_cvars.h"
 #include "r_3dfloors.h"
 
+CVAR(Int, r_3dfloors, true, 0);
+
+namespace swrenderer       
+{
+
 // external variables
 int fake3D;
 F3DFloor *fakeFloor;
@@ -28,8 +33,6 @@ HeightLevel *height_cur = NULL;
 int CurrentMirror = 0;
 int CurrentSkybox = 0;
 
-CVAR(Int, r_3dfloors, true, 0);
-
 // private variables
 int height_max = -1;
 TArray<HeightStack> toplist;
@@ -160,3 +163,4 @@ void R_3D_LeaveSkybox()
 	CurrentSkybox--;
 }
 
+}