Adding Stats savefile

Adding a separate savefile for stats (seconds played). This allows to:

• Reset the game without affecting stats
• Sync stats with Steam Cloud
• Save stats to disk frecuently

This change will reset the count on the amount of time played. If you want to get the 2 hour achievement you can left the game open (unpaused!) so the time advances.

Remember that you can check the amount of time played in the ingame clock!