Enchantments implementation

This adds basic enchantment functionality.

This PR includes:
- Serialization (map and nbt) of enchantments (see #77 )
- GlowMetaEnchantedBook (implements EnchantmentStorageMeta) (see #77)
- Saving and loading of the xpSeed tag (in GlowHumanEntity)
- Enchantment and level calculation for 1.8
- Enchantment Table GUI (see #1)
- EnchantItemEvent and PrepareItemEnchantEvent (see #28)

This PR does NOT include:
- Enchantments created by anvils or commands
- the enchantment's functionality (a tool enchanted with efficiency will never lost this enchantment again, but it behaves like a 'normal' tool)

https://github.com/GlowstoneMC/Glowkit/pull/63