Quality-of-life updates

[list] [*] The game displays the current floor number when using a door. [*] Tutorial text changed to highlight that the parasite is the player's hitbox. [*] Enemies ignore you for a brief amount of time when using a door. [*] Losing a normal level no longer resets the adquired tools. [*] "Main menu" buton removed from pause menu to prevent "going to main menu and restarting level" exploit. [/list]