Add missing materials to Step. Fixes BUKKIT-4074

When Minecraft 1.4.6 was released, Nether Brick texturing to steps
was added. Minecraft 1.5 added Quartz texturing to steps. When Bukkit
was updated to these version the textures for steps were not applied.

Currently it is not possible to set the texture of steps to quartz
or nether brick. This commit fixes that by adding the respective values
to the allowable materials list.
Fix missing closing bracket in addEnchantment. Fixes BUKKIT-4126

Prior to this commit the message would display as "...(given #, bounds
are # to #". This commit changes that by adding the missing bracket to
the end of the statement. This is strictly a visual error.
Use command block's world for /gamerule. Fixes BUKKIT-3274

In vanilla, gamerules are global, across all worlds. Maps created for
vanilla that use command blocks expect this behavior, which is broken
when they are placed on a world that is not the default world (world #0).

This commit changes that by using the command block's current world when
executing the command, forcing the game rules executed to be executed in
the world the command block is currently in.
Add source encoding to the maven compiler plugin.

This change adds the source encoding to the maven compiler plugin, which
will strictly enforce build consistency on multiple platforms and address
possible compilation issues on some of the source files. The source
encoding unintuitively is system-specified by default.
Deprecate magic values
Expand javadocs for all 3 command pre-processing events
Clarify Inventory.contains(ItemStack, amount) and add @see

... to containsAtLeast(ItemStack, amount) as well as a slight wording change to containsAtLeast.
Slightly better wording for contains()
Reword on containsAtLeast()
Fix second lines, add p-tag
Add javadoc to ItemDespawnEvent
Compliant formatting:

 - no closing of <li> tags
 - only exact tokens in <code> tags, not placeholders
Fix capitalization
Document Entity/PlayerPortalEvents and TravelAgent
Multiple fixes/changes
* Add more details on TravelAgent's description
* Don't repeat the same {@link} tag in the same comment block
* Use labels in every {@link} tag
Add details on what a portal creation involves
Multiple fixes
* Limit line-length to 78 chars
* Link to Getters instead of fields
* Don't use labels if not needed
* Don't capitalize @param and @return tags
Make /spreadplayers command work. Fixes BUKKIT-4720
Merge #37

Thanks @riking

commit bd5277b9275f1405d2918fbad523b5bfaba069dd
Author: riking
Date:   2013-08-20 14:32:31 -0700

Add javadoc to ItemDespawnEvent
Merge #40

Thanks @Ribesg

commit 6c8fd142c41370aadca0e1df1d1ef7bf80a42c6d
Author: Ribesg
Date:   2013-09-03 10:59:56 +0200

Multiple fixes

 * Limit line-length to 78 chars

 * Link to Getters instead of fields

 * Don't use labels if not needed

 * Don't capitalize @param and @return tags

commit 268f72838b7840ce297dfcec332e883323257b2d
Author: Ribesg
Date:   2013-09-03 10:46:46 +0200

Add details on what a portal creation involves

commit c4bc46560b95bc7e70a1154d2c26e7497674a44d
Author: Ribesg
Date:   2013-09-02 19:49:46 +0200

Multiple fixes/changes

 * Add more details on TravelAgent's description

 * Don't repeat the same {@link} tag in the same comment block

 * Use labels in every {@link} tag

commit 6ac5892474a519f20a785a93229d340c29d8cd3b
Author: Ribesg
Date:   2013-09-02 19:34:25 +0200

Document Entity/PlayerPortalEvents and TravelAgent