instance zone is finished.

Reported by: ShinichiYao  

- Replaced SkillData.getInstance().getSkill with SkillHolder DTO;
- Replaced Skill versions of doCast and doSimultaneousCast with
SkillHolder ones;
- Fixed typo on Sanctum of the Lords of Dawn instance zone;
- Some cleanup.

 - Reported by: ShinichiYao

- Based on St3eT's work

Fixed minor typos.

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

L2J/L2J_Server@2f3dca83e5317b7471ac1bf472067e9ad1a85003

	* Unhardcoded some HTMLs.
	* Renamed `INSTNACEID` to `TEMPLATE_ID`.
	* Fixed missuse of template ID and instance ID in multiple instances.
	* Fixed Ranku, Demon Prince, Urban Area, Monastery Of Silence, Library Of Sages.

Reported by: !FinalDestination, !CostyKiller, JOJO

	* Also including new admin command !//setinvis which will toggle visibility/invisibility of your target.

	* Fixed some messy code.

* Reviewed by: malyelfik, Zoey76, !UnAfraid, Adry_85