Minor fixes and befriended the API with Java

Some messages gave an error on the Spigot core

API

• The API is now more Java-friendly
• Added new methods to the API: getInspectorByPlayer(), getInspectors(), addLog()
• Fixed the behavior of methods in CheckedPlayer(): setTimer(), getTimer(), hasTimer()
• You can now pass null to methods in the API
  For Boolean values, no validation is needed on your part; it will return false if null
• The stopAll() method now returns a list of CheckedPlayer.
  It includes those for whom the check was stopped.