Customizable 'TrashBlocks' and Wilderness placement delay

List of "Trash" blocks were hard coded into BlockEventHandler.java for specific block types. This change allows Trash Blocks to be set via the GriefPrevention.Claims.TrashBlocks configuration setting. The default is the original hard-coded value.

When placing non-trash blocks in the wilderness, the plugin counts down from a hard-coded value of 15, so every 15th block will trigger the text message about other players being able to change the claim. This value is now read from the configuration entry GriefPrevention.Claims.WildernessWarningBlockCount. It defaults to the original hard-coded 15 as well. 0 will disable the message entirely, like the WarnWhenBuildingOutsideClaims configuration entry.