Merge pull request #161 from ACzChef/master

Added item_pre_enchant. Thanks ACzChef!
Made vault messages while compiling disappear.
Reversed /reloadaliases --blacklist wording, to --whitelist. Only the wording has changed, otherwise, the functionality is the same.
Continued with query().

Also, changed the signature of Event.bind() to send a BindableEvent instead of just prefilters. This could potentially break extensions.
Added entity_line_of_sight(), entity_can_see(), *_entity_air(), *_entity_max_air(), generate_tree(), *_gamerule(), *_PVP(), *_difficulty() and shutdown_server().
Fixed NPE in all_entities(), spawn_mob() and drop_item() (due to inexisting world or invalid sender).
Added the possibility to choose a world for all_players().
Added the possibility to keep the random seed in create_word() if we want to choose the environment or the generator, and to set a string for seed (will be its hashcode).
Added the possibility to choose the way the item will be spawned in drop_item().
Fixed gamemode lists in documentation.
ploc() now returns an associative array, like all other location arrays.
Added reflect_value_source, and shaded in a few classes that were requiring a hard dependency on WE.
Moved *_difficulty, *_PVP and *_gamerule functions from Minecraft to World class, and removed shutdown_server.
Fixed issues where exceptions would ruin profile points.

All profile point starts are followed by try {} finally { p.stop(); } to ensure that stop is always run after it is started.
Re-added and optimized server_shutdown(), and fixed a test that was failing due to the ploc() modification.
Updated doc, forgot a line
Added the refactor tool to the data manager (finally).
Various minor improvements.
Merge origin/master
Added more verbose output to the refactor tool.
Merge pull request #162 from Hekta/master

Added entity_line_of_sight(), entity_can_see(), *_entity_air(), *_entity...
Fixed http_request example 2 in docs.
Fixed ploc(), that was returning one block above the block upon which the player is standing on, due to the last change.
Merge pull request #163 from Hekta/master

Fixed ploc(), that was returning one block above the block upon which the player is standing on, due to the last change.
Refactored packages.
Tenative fix for hidden bugs in extension loading.