Add Block, javadoc cleanup

Add ignoresCancelled to SpongeEventHandler

Signed-off-by: Chris Sanders <zidane@outlook.com>
Add majority of the lifecycle events

@cpw feel free to remove any un-necessary for Sponge

Signed-off-by: Chris Sanders <zidane@outlook.com>
Add Item/ItemBlock

Signed-off-by: Chris Sanders <zidane@outlook.com>
Correct my faiure to follow conventions

Signed-off-by: Chris Sanders <zidane@outlook.com>
Added Licence to Item and ItemBlock
Merge pull request #14 from lclc98/master

Added licence to Item and ItemBlock
Inventory interface

Adding core inventory interface with essential add/get/clear methods. Includes
empty `ItemStack` interface - awaiting `Material` interface in pending PRs.