Adds additional dice!

Places where the D6 and D20 spawned (the library and perma) now spawn with a dice bottle. Said dice bottles now contain a D2, D4, D8, D10, and D12 in addition to the preexisting D6 and D20 for a richer meta-roleplaying experience.

This also fixes an obscure bug where dice could be generated invisible because their initial face value was set to 0.

Additionally this fixes the grammar of dice descriptions, which were not using the singular "die".

http://i.imgur.com/UPHsAkw.png