Added visualization of chunk limits

Signed-off-by: Moritz Schmale <narrow.m@gmail.com>
Formatting

Signed-off-by: Moritz Schmale <narrow.m@gmail.com>
Made grid-duration configurable

Empty chunks only draw one block at 0,0 of the chunk

Signed-off-by: Moritz Schmale <narrow.m@gmail.com>
Renamed config values

made none use glass
Added different layouts for each level
Added possibility to disable the auto-cleanup, this works like so:

    /animals show keep

this will disable automatic cleanup, hide the grid later with

    /animals hide
Added commands documentation to README.md
Formatting, take 2
Revert adding a plugin reference to BaseCommand
Formatting, take 3
Merge pull request #9 from narrowtux/master

Visualize limits