I'm In Danger!

Added config setting for "Dangersense Mode"
This allows you to specify how players can obtain dangersense
0 - Players just naturally always have dangersense (default)
1 - Adds dangersense potions to the game
2 - Adds dangersense enchantment to the game
3 - Adds dangersense potions and enchantment to the game

Note that the clients should have the same dangersense mode selected as the server, and that if you change the mode in such a way that the potions or enchantment WERE in a world but NO LONGER ARE, then YOU MAY NEED TO MAKE A NEW WORLD!  This option is intended as a decision you make AHEAD OF TIME!