Tell the player that their game mode was changed

Resolves https://github.com/GlowstoneMC/Glowstone/issues/397
Updated Enchanting inventory to include new slot.
Added cause-specific damage methods to Damageable.
Fixed facing methods for fence gates.
Updated magic values for Skull directions.

Minecraft 1.8 switches the representations of east and west.
Added API for manipulating banners and banner patterns.

Banner blocks have facing, base color, and pattern. Banner patterns are a
list of layers, which have a shape and color.
Added missing effects from Minecraft 1.7.
Updated resource packs for 1.8 changes, with resource pack event.

Minecraft 1.8 added the ability to set the player's texture pack using not
only a URL as before, but also some identifier (ideally the SHA-1 hash of
the ZIP file to be downloaded by the client). That identifier, if an empty
string, will force the client to not consider the identifier and simply
re-download the resource pack.

The client currently has several bugs relating to resource packs and
therefore the newly added event (fired after the setting of a resource
pack) may fire illogically.
Fixed maven warnings about missing plugin version.