use saner format for screenshot names by default

src/engine/texture.cpp

@@ -2960,8 +2960,25 @@ void screenshot(char *filename)
     }
     else
     {
-        defformatstring(name)("screenshot_%d", totalmillis);
-        concatstring(buf, name);
+        string sstime;
+        time_t t = time(NULL);
+        size_t len = strftime(sstime, sizeof(sstime), "%Y-%m-%d_%H.%M.%S", localtime(&t));
+        sstime[min(len, sizeof(sstime)-1)] = '\0';
+        concatstring(buf, sstime);
+
+        const char *map = game::getclientmap(), *ssinfo = game::getscreenshotinfo();
+        if(map && map[0])
+        {
+            concatstring(buf, "_");
+            concatstring(buf, map);
+        }
+        if(ssinfo && ssinfo[0])
+        {
+            concatstring(buf, "_");
+            concatstring(buf, ssinfo);
+        } 
+        
+        for(char *s = buf; *s; s++) if(iscubespace(*s)) *s = '-'; 
     }
     if(format < 0)
     {

src/fpsgame/fps.cpp

@@ -562,6 +562,11 @@ namespace game
         return showmodeinfo && m_valid(gamemode) ? gamemodes[gamemode - STARTGAMEMODE].info : NULL;
     }
 
+    const char *getscreenshotinfo()
+    {
+        return server::modename(gamemode, NULL);
+    }
+
     void physicstrigger(physent *d, bool local, int floorlevel, int waterlevel, int material)
     {
         if     (waterlevel>0) { if(material!=MAT_LAVA) playsound(S_SPLASH1, d==player1 ? NULL : &d->o); }

src/shared/igame.h

@@ -58,6 +58,7 @@ namespace game
     extern void dynentcollide(physent *d, physent *o, const vec &dir);
     extern const char *getclientmap();
     extern const char *getmapinfo();
+    extern const char *getscreenshotinfo();
     extern void resetgamestate();
     extern void suicide(physent *d);
     extern void newmap(int size);