Multiple changes, read more

* Implemented HeartbeatUtility
* simplified the SQL files
* Added a dummy inventory button

server/Inventory/inventory_manager.cpp

@@ -21,14 +21,3 @@
 */
 #include "inventory_manager.hpp"
 
-static const char* CREATE_CHARACTER_ITEMS = "INSERT INTO CharacterItems (character, item) VALUES (?1, ?2);";
-
-static const char* DELETE_CHARACTER_ITEMS = "DELETE FROM CharacterItems WHERE (character=?1, item=?2);";
-
-static const char* CREATE_CHARACTER_EQUIPMENT = "INSERT INTO CharacterEquipment (character, item) VALUES (?1, ?2);";
-
-static const char* DELETE_CHARACTER_EQUIPMENT = "DELETE FROM CharacterEquipment WHERE (character=?1, item=?2);";
-
-int InventoryManager::CreateItem(int owner, ItemType itemType) {
-	sqlite3_stmt* statement = nullptr;
-}