Custom category and multiple new features and enhancements!

New: new Custom category, thanks to Phoetrix! You can create your own sub-categories and increase their statistic with the new /aach add command!
New: ListColorNotReceived parameter to allow changing the /aach list colour of not yet received achievements.
New: per-category cooldown. Simply replace the old StatisticCooldown parameter with the new style if you want to use this feature. The Milks category is now supported as well.
Improvement: more robust database connection handling to avoid connection errors.
Improvement: /aach reset now supports sub-categories, for instance /aach reset Breaks.sand DarkPyves.
Improvement: boosted performance of the /aach top, /aach week and /aach month commands.
Improvement: updated /aach info command.
Fix: various fixes to make the plugin run more smoothly.
Other: Finnish translation, thanks to Rsl1122!

PlaceholderAPI, command reward messages and more!

New: custom messages for command rewards, thanks to Supertassu! Use the following syntax:

Reward:
  Command:
    Execute: "say §7ALERT: §4PLAYER§7 has become the Stone God!"
    Display: Become the Stone God!

New: PlaceholderAPI support, thanks to Phoetrix! You can use the placeholders he listed in #269.
Improvement: refactored some database code for better maintainability.
Fix: extended Minecraft 1.7.9/1.7.10 support. Refer to the updated Wiki to install the plugin on these old Minecraft versions.

New configuration options

New: implemented AdditionalConnectionOptions configuration option to allow tuning database connections.​
New: implemented HoverableReceiverChatText configuration option to group texts into a single hover when a player receives an achievement.​
Other: various behind the scene improvements.​

Polish translation, minor fixes and improvements

Improvement: players are no longer affected by statistic cooldowns when they have completed all achievements in the category.
Fix: removed some warning messages non relevant to old Minecraft versions.
Other: Polish translation by Garixer!

Quick fixes to /aach list

Fix: fixed some issues with the /aach list command. Thanks to @aurel85 for pointing this out!

Pagination, new options and many other improvements

New: added AchievementNotStarted, AchievementStarted, AchievementReceived, BackButton, PreviousButton and NextButton items to gui.yml, allowing further customisation of the /aach list command.
New: implemented a nice pagination system within the GUI.
New: added a ChatHeader configuration option to more finely customise the header in the displayed messages.
Improvement: players will receive achievements even if they have gone over the value set in the configuration. You can now freely add new achievements for any category without worrying about the thresholds.
Improvement: dropped support for Java 7, which enabled to modernise some parts of the code.
Improvement: refactored some classes and cleaned up the project to make it more maintainable and facilitate contributions.
Fix: prevented some cases where the player could navigate through the GUI using his personal inventory.
Fix: made configuration parsing more robust to avoid errors due to unneeded whitespaces.

Pet Master 1.7 support

Other: added support for Pet Master 1.7.

Oxygen reward type

New: implemented additional IncreaseMaxOxygen reward type. A value of 30 corresponds to one bubble in the oxygen bar.

Cooldown fix

Fix: cooldown messages for the MusicDiscs category are now displayed correctly.

IgnoreAFKPlayedTime parameter and other improvements

New: added IgnoreAFKPlayedTime configuration parameter to ignore played time when user is AFK (requires Essentials)!

Improvement: overall performance enhancements and various other code improvements.

Fix: fixed configuration files issues when upgrading to newer versions of the plugin.