Moved to Maven instead of Gradle.
Using proper project structure and package structure.

Fixed minor typos.

Moving all files to main folder.
Using Gradle to define, manage dependecies and build the project.
Upgraded Gradle wrapper.

Reviewed by: Zoey76, !UnAfraid

	* Proper GPLv3 license.
	* Updated all Java DP files.
	* Added missing license to the following files:
		* !FirstClassTransferTalk
		* !AdminInstanceZone
	* Updated Eclipse preferences for new files (header).
		* ''Same'' settings as Core.

	* Wondrous Cubic - 1 time use should be consumed upon usage.
	* Added more missing GPL notices.
	* Implemented Calculator item handler.
	* Moved some high time reuses from items skills to it's items, it's a temp fix for missing global skill reuse, since item reuse is global to all classes.
	* Removed custom check based on skill type for Extractable skills with high reuse not being able to be used in sub-classes.

BETA: Minor fix for [8613], let's restrict all items with Extractable Skills, not only the ones that consume an item, thanks UnAfraid and baluu for report.

	* Using same Code warning/error configuration than core.
	* Fixed respective warnings and errors.
	* Fixing Extractable Skills restriction properly.
		1. Unhardcode Skills Ids.
		1. Now only Item Skills are restricted.
		1. Items with consume count won't be consumed without giving the reward.
		1. Applied to reuse time greater than 5 seconds, there is no point on restrict item skills with less reuse time.
		1. Unhardcoded system message for item reward.
	* Hellbound fixes:
		1. Hellbound should start closed at server start (level 0), thanks Trev.
		1. Quarry ClassCastException fix.
	* Q290_ThreatRemoval removed unnecessary int cast.
	* Q636_TruthBeyond proper method to get an int.
	* Skill Santa Claus' Gift - Luck(22018) typo fix.

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JAVA/SQL: Divide ItemSkills handler to the several separated handlers, unhardcoding checks for olympiad and mana potions, thanks _DS_

JAVA: Fix for "ItemSkills.java" to solve a issue with incorrect reuse time in Mana Potion, thanks Janiii.

JAVA/XML/SQL: DP part for [L4017] (Greater elixirs values are guessed 2x from normal), included fix for instance name display on shift-click, thanks _DS_.

Potions.java handler removed. ItemSkills handler reworked: if itemConsumeId not set - consume currently used item. Thanks _DS_

handler defined inside etcitem table
require [L3107]