[BUKKIT-5319] - Add support for reading and modifying chunk inhabited tiimes



Since v1.6.x, vanilla minecraft has incorporated a feature for maintaining a cumulative total time that each chunk has been kept loaded due to player presence. This data, which is not currently available through the API, offers a number of opportunities for mod developers, as a number of vanilla behaviors are driven by it:
1) Odds of armor on skeletons and zombies
2) Changes for enchantments on mob equipment
In addition, one can see other mods benefiting from similar considerations - boosting the chances of certain mod-specific activities based on how long a given area has been 'inhabited': possibly causing more mobs to be 'drawn' to the popular area, and the like.

The option to manipulate the value is of interest, as well, for the same reasons. Mods which allow an area to gradually act like it is no longer inhabited after being vacated, or which should act as though it has been inhabited for a long time (despite being newly created or edited), are both appealing possibilities.

See https://bukkit.atlassian.net/browse/BUKKIT-5319 for details.

See https://github.com/Bukkit/CraftBukkit/pull/1321 for CraftBukkit PR.