[Pts] Arrivée du Mentoring

MENTORING
* New Mentoring system allows you to set your character's level below what it actually is, whether you're on your own or playing with a lower-level character.
* Mentoring is available for characters of level 11+ and you can only reduce your current level, not increase it.
* The new Set Ascended Mentor Level menu option now appears when right clicking your own character portrait. You can choose what level you'd like to set your character to from this option.
* When right-clicking the portrait of another character, the menu option to set your mentor level to the target's level appears.
* While mentoring, your stats, abilities, regeneration, etc. will be temporarily reduced in line with the target level.
* Grouped characters using mentoring will receive bonus experience as long as the character with the lower natural level remains within 2 levels of the mentor and the mentor remains at least 5 levels below their natural level.