Add basic PR guidelines
Added irc webclient URL
World/chunk interface

Adding core world/chunk interface.

*Note* `World` will need a way to return all loaded chunks,
but we'll need some discussion as to what containing object structure
should be used.
Add Block, javadoc cleanup

Add ignoresCancelled to SpongeEventHandler

Signed-off-by: Chris Sanders <zidane@outlook.com>
Merge pull request #1 from SpongePowered/master

mearge