Add cs_find_ent_by_class and fix documentation

plugins/include/cstrike.inc

@@ -351,14 +351,20 @@ native bool:cs_get_c4_defusing(c4index);
 native cs_set_c4_defusing(c4index, bool:defusing);
 
 /**
- * Creates an entity.
+ * Creates an entity using Counter-Strike's custom CreateNamedEntity wrapper.
  *
- * @note  Similar as create_entity() native from engine module, with the difference that in Counter-Strike
- *        to improve lookup performance on entities, the classname is hashed and saved in a global list.
- *        This means for classname, game uses a custom function which checks that list instead of calling pfnFindEntityByString.
- *        You would want to use this native if you want having custom entities to be known by the game.
- *        E.g. By creating a "weaponbox" entity, this will be automatically deleted by game on map restart.
- *             With engine version, you would have to remove it manually.
+ * @note Unlike other mods CS keeps track of entities using a custom hashtable.
+ *       This function will add entities to this hashtable, providing benefits
+ *       over the default engine functions (used by create_entity() for example):
+ *       - Storing entities in a hashtable allows CS to improve classname lookup
+ *         performance compared to functions like FindEntityByString that usually
+ *         have to loop incrementally through all entities.
+ *       - As CS exclusively uses the hashtable for classname lookup, entities
+ *         created using the default engine functions will not be found by the
+ *         game. For example "weaponbox" entities are supposed to be
+ *         automatically cleaned up on round restart but are not considered if
+ *         they have not been added to the hashtable.
+ * @note CS's faster hashtable lookup can be utilized with cs_find_ent_by_class()
  *
  * @param classname     Entity class name
  *
@@ -366,6 +372,25 @@ native cs_set_c4_defusing(c4index, bool:defusing);
  */
 native cs_create_entity(const classname[]);
 
+/** 
+ * Finds an entity in the world using Counter-Strike's custom FindEntityByString
+ * wrapper.
+ *
+ * @note Unlike other mods CS keeps track of entities using a custom hashtable.
+ *       This function utilizes the custom hasthable and allows for considerably
+ *       faster classname lookup compared to the default engine functions (used
+ *       by find_ent_by_class() for example).
+ * @note This exclusively considers entities in the hashtable, created by the
+ *       game itself or using cs_create_entity().
+ *
+ * @param start_index   Entity index to start searching from. -1 to start from
+ *                      the first entity
+ * @param classname     Classname to search for
+ *
+ * @return              Entity index > 0 if found, 0 otherwise
+ */
+native cs_find_ent_by_class(start_index, const classname[]);
+
 /**
  * Called when CS internally fires a command to a player.  It does this for a few 
  * functions, most notably rebuy/autobuy functionality.  This is also used to pass