Move extesnsions_key literal to squirrel.h

SquiLu/include/squirrel.h

@@ -468,6 +468,7 @@ SQUIRREL_API void sq_pushregistrytable(HSQUIRRELVM v);
 SQUIRREL_API SQRESULT sq_getonregistrytable(HSQUIRRELVM v);
 SQUIRREL_API SQRESULT sq_setonregistrytable(HSQUIRRELVM v);
 
+#define SQ_EXTENSIONS_KEY _SC("sq__Extensions")
 typedef struct {
     const char* module_name;
     SQFUNCTION module_load_func;

SquiLu/squirrel/sqapi.cpp

@@ -680,12 +680,11 @@ SQRESULT sq_setonregistrytable(HSQUIRRELVM v)
 int sq_preload_modules(HSQUIRRELVM v, sq_modules_preload_st *modules){
     int result = 0;
     int saved_top = sq_gettop(v);
-    #define EXTENSIONS_KEY _SC("__Extensions")
-    sq_pushliteral(v, EXTENSIONS_KEY);
+    sq_pushliteral(v, SQ_EXTENSIONS_KEY);
     if(sq_getonregistrytable(v) != SQ_OK){
         //create a table for Extensions
         sq_newtable(v);
-        sq_pushstring(v, EXTENSIONS_KEY, -1);
+        sq_pushstring(v, SQ_EXTENSIONS_KEY, -1);
         sq_push(v, -2);
         sq_setonregistrytable(v);
     }