WorldGuard BuildWhitelist

* Renamed the plugin to WorldGuardBuildWhitelist * Reworked the WorldGuard integration for block breaking and placing * Added cleaner support for allowing specific blocks inside WorldGuard regions * Players can now break or place whitelisted blocks without extra deny-message workarounds * Removed the need to disable WorldGuard particle effects for this plugin to feel clean * The plugin is now drag-and-drop: install it, set the flags, and it works * Kept support for the existing custom-block-break and custom-block-place flags * Cleaned up the internal package and class structure * Improved material parsing by using Bukkit material matching * Added validation so only real block materials can be used in the flags