integrated automatic embedded map config files

This patch enables an option to keep the map config embedded in the map
file - with autogenerated content. Any changes to map config data will be
written with the map. This includes data by loadnotexture, loadsky,
mapmodel, texture, fog, fogcolour, mapsound and shadowyaw. Once enabled,
all changes with those commands become persistent to the map.

New variables:

mapsoundchanged
  Set to "1" with every command that changes mapsound slots. Should be
  used to trigger a rebuild of mapsound menus.

New/changed commands:

mapsound
  Now returns the number of the created slot.

mapmodel
  Now returns the number of the created slot.

texture
  Now returns the number of the created slot.

loadsky
  Is now a builtin string variable (instead of a command), which means,
  that the current value can easily be retrieved or edited.
  The skymap name in the argument is now required to start with
  "textures/skymaps/" - but that part of the path can be omitted.
  examples:
    loadsky steini/steini2 (loads textures/skymaps/steini/steini2_*)
    loadsky textures/skymaps/steini/steini2 (same)
    loadsky ../foo/bar (loads textures/foo/bar_*)
    echo $loadsky

getnotexture
  Returns the current "notexture" path. (Set by loadnotexture)

dumpmapconfig (available for debug binaries only)
  Writes the current automatically generated map config to
  dumpmapconfig.txt.

DOCREF mapsoundchanged mapsound mapmodel texture loadsky getnotexture

source/src/texture.cpp

@@ -481,28 +481,49 @@ Texture *createtexturefromsurface(const char *name, SDL_Surface *s)
 struct Slot
 {
     string name;
-    float scale;
+    float scale, orgscale;
     Texture *tex;
     bool loaded;
 };
 
 vector<Slot> slots;
 
-void texturereset() { if(execcontext==IEXC_MAPCFG) slots.setsize(0); }
+COMMANDF(texturereset, "", ()
+{
+    if(execcontext==IEXC_MAPCFG)
+    {
+        slots.setsize(0);
+        flagmapconfigchange();
+    }
+});
 
 void texture(float *scale, char *name)
 {
+    intret(slots.length());
     Slot &s = slots.add();
     copystring(s.name, name);
-    path(s.name);
     s.tex = NULL;
     s.loaded = false;
+    s.orgscale = *scale;
     s.scale = (*scale > 0 && *scale <= 2.0f) ? *scale : 1.0f;
+    flagmapconfigchange();
 }
 
-COMMAND(texturereset, "");
 COMMAND(texture, "fs");
 
+const char *gettextureslot(int i)
+{
+    static string res;
+    if(slots.inrange(i))
+    {
+        Slot &s = slots[i];
+        defformatstring(d)("%d", int(s.orgscale));
+        formatstring(res)("texture %s \"%s\"", s.orgscale == int(s.orgscale) ? d : floatstr(s.orgscale), s.name);
+        return res;
+    }
+    else return NULL;
+}
+
 Texture *lookuptexture(int tex, Texture *failtex, bool trydl)
 {
     Texture *t = failtex;
@@ -511,13 +532,13 @@ Texture *lookuptexture(int tex, Texture *failtex, bool trydl)
         Slot &s = slots[tex];
         if(!s.loaded)
         {
-            defformatstring(pname)("packages/textures/%s", s.name);
+            defformatstring(pname)("packages/textures/%s", path(s.name, true));
             s.tex = textureload(pname, 0, true, true, s.scale, trydl);
             if(!trydl)
             {
-            if(s.tex==notexture) s.tex = failtex;
-            s.loaded = true;
-        }
+                if(s.tex==notexture) s.tex = failtex;
+                s.loaded = true;
+            }
         }
         if(s.tex) t = s.tex;
     }
@@ -555,38 +576,52 @@ void reloadtextures()
 }
 
 Texture *sky[6] = {NULL, NULL, NULL, NULL, NULL, NULL};
-static string skybox;
 
-void loadsky(char *basename, bool reload)
+SVARF(loadsky, "", { loadskymap(false); });
+
+void loadskymap(bool reload)
 {
     const char *side[] = { "lf", "rt", "ft", "bk", "dn", "up" };
-    if(reload) basename = skybox;
-    else copystring(skybox, basename);
+    const char *legacyprefix = "textures/skymaps/";
+    if(!reload)
+    {
+        int n = strlen(legacyprefix);
+        if(!strncmp(loadsky, legacyprefix, n))
+        { // remove the prefix
+            char *t = loadsky;
+            loadsky = newstring(loadsky + n);
+            delstring(t);
+        }
+        flagmapconfigchange();
+    }
     loopi(6)
     {
-        defformatstring(name)("packages/%s_%s.jpg", basename, side[i]);
+        defformatstring(name)("packages/%s%s_%s.jpg", legacyprefix, loadsky, side[i]);
         sky[i] = textureload(name, 3);
         if(sky[i] == notexture && !reload && autodownload)
         {
-            defformatstring(dl)("packages/%s", basename);
+            defformatstring(dl)("packages/%s%s", legacyprefix, loadsky);
             requirepackage(PCK_SKYBOX, dl);
             break;
         }
     }
 }
 
-COMMANDF(loadsky, "s", (char *name) { loadsky(name, false); intret(0); });
 void loadnotexture(char *c)
 {
     noworldtexture = notexture; // reset to default
+    *mapconfigdata.notexturename = '\0';
     if(c[0])
     {
         defformatstring(p)("packages/textures/%s", c);
         noworldtexture = textureload(p);
         if(noworldtexture==notexture) conoutf("could not load alternative texture '%s'.", p);
     }
+    flagmapconfigchange();
 }
+
 COMMAND(loadnotexture, "s");
+COMMANDF(getnotexture, "", () { result(mapconfigdata.notexturename); });
 
 void draw_envbox_face(float s0, float t0, float x0, float y0, float z0,
                       float s1, float t1, float x1, float y1, float z1,