introduce a constant for no category

docs/sdk/definition/category.xml

@@ -15,6 +15,11 @@
           <col>Description</col>
 		  <col>Default plane</col>
         </rowh>
+        <row>
+          <col>C4D_None</col>
+          <col>No category.</col>
+          <col></col>
+        </row>
         <row>
           <col>C4D_StaticBack</col>
           <col>Immovable object.</col>

docs/sdk/script/fn/C4D_None.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<!DOCTYPE funcs
+  SYSTEM '../../../clonk.dtd'>
+<?xml-stylesheet type="text/xsl" href="../../../clonk.xsl"?>
+<funcs>
+  <const>
+    <title>C4D_None</title>
+    <category>Objects</category>
+    <subcat>Category</subcat>
+    <version>6.0 OC</version>
+    <syntax><rtype>int </rtype></syntax>
+    <desc>No category, can be used for GUI and HUD objects. Only set this category for an object if you are aware of the consequences.</desc>
+    <related>
+      <funclink>GetCategory</funclink>
+      <funclink>SetCategory</funclink>
+    </related>
+  </const>
+  <author>Maikel</author><date>2015</date>
+</funcs>

src/object/C4Def.cpp

@@ -197,6 +197,7 @@ void C4Def::CompileFunc(StdCompiler *pComp)
 	const StdBitfieldEntry<int32_t> Categories[] =
 	{
 
+		{ "C4D_None",                     C4D_None                },
 		{ "C4D_StaticBack",               C4D_StaticBack          },
 		{ "C4D_Structure",                C4D_Structure           },
 		{ "C4D_Vehicle",                  C4D_Vehicle             },

src/object/C4Def.h

@@ -38,6 +38,7 @@
 #include <set>
 
 const int32_t
+C4D_None           =     0,
 C4D_All            =    ~0,
 C4D_StaticBack     =  1<<0,
 C4D_Structure      =  1<<1,

src/object/C4ObjectScript.cpp

@@ -2343,6 +2343,7 @@ static bool FnCreateParticleAtBone(C4Object* Obj, C4String* szName, C4String* sz
 
 C4ScriptConstDef C4ScriptObjectConstMap[]=
 {
+	{ "C4D_None"               ,C4V_Int,          C4D_None},
 	{ "C4D_All"                ,C4V_Int,          C4D_All},
 	{ "C4D_StaticBack"         ,C4V_Int,          C4D_StaticBack},
 	{ "C4D_Structure"          ,C4V_Int,          C4D_Structure},