permadeath and limited saves

[Chriz76]

• When starting a new game the player can choose the regular default mode (unlimited saves and lives) or one of the new modes (Unlimited lives, 50, 10 ,3, 1 life)
• The mode and remaining lives is displayed on the hero overview page.
• There can be only one savegame for a limited saves game: Saving a limited save game ends the game. Loading a limited saves game deletes the save slot.
• Heros now have a hero ID and there is a cheat prevention that checks if the savegame was already continued.
• Added some warning and explanation dialogues