Use abs instead of saturate to do double-sided lighting on meshes

* This means we don't need to care about winding making normals inside
  out, and in this case it's not a bad thing to light backfaces I think.

renderdoc/data/glsl/mesh.frag

@@ -50,7 +50,7 @@ void main(void)
 	{
 		vec3 lightDir = normalize(vec3(0, -0.3f, -1));
 
-		color_out = vec4(RENDERDOC_GenericFS_Color.xyz*clamp(dot(lightDir, IN.norm.xyz), 0.0f, 1.0f), 1);
+		color_out = vec4(RENDERDOC_GenericFS_Color.xyz*abs(dot(lightDir, IN.norm.xyz)), 1);
 	}
 	else //if(type == MESHDISPLAY_SOLID)
 	{

renderdoc/data/hlsl/debugdisplay.hlsl

@@ -253,7 +253,7 @@ float4 RENDERDOC_MeshPS(wireframeV2F IN) : SV_Target0
 	{
 		float3 lightDir = normalize(float3(0, -0.3f, -1));
 
-		return float4(WireframeColour.xyz*saturate(dot(lightDir, IN.norm)), 1);
+		return float4(WireframeColour.xyz*abs(dot(lightDir, IN.norm)), 1);
 	}
 	else //if(type == MESHDISPLAY_SOLID)
 		return float4(WireframeColour.xyz, 1);