Add named slice positions for vertex shaders

src/graphics/C4Shader.cpp

@@ -15,6 +15,10 @@ C4ShaderPosName C4SH_PosNames[] = {
 	{ C4Shader_PositionLight,		 "light" },
 	{ C4Shader_PositionColor,		 "color" },
 	{ C4Shader_PositionFinish,		 "finish" },
+
+	{ C4Shader_Vertex_TexCoordPos,		"texcoord" },
+	{ C4Shader_Vertex_NormalPos,            "normal" },
+	{ C4Shader_Vertxe_PositionPos,          "position" }
 };
 
 C4Shader::C4Shader()

src/graphics/C4Shader.h

@@ -29,6 +29,7 @@ const int C4Shader_LastPosition = 256;
 
 // Positions in vertex shader
 const int C4Shader_Vertex_TexCoordPos = 50;
+const int C4Shader_Vertex_NormalPos = 60;
 const int C4Shader_Vertex_PositionPos = 80;
 
 class C4Shader