#1116 #1117 Add command usage hints and remove unused message keys

- Add usage message on argument mismatch where available
- Remove unused message keys
- Create tool task to search for a message key's usages and to find unused keys

src/test/resources/fr/xephi/authme/message/messages_test.yml

@@ -1,7 +1,7 @@
 # Sample messages file
 
 unknown_user: 'We''ve got%nl%new lines%nl%and '' apostrophes'
-unsafe_spawn: '&cHere we have&bdefined some colors &dand some other &lthings'
+login: '&cHere we have&bdefined some colors &dand some other &lthings'
 reg_voluntarily: 'You can register yourself to the server with the command "/register <password> <ConfirmPassword>"'
 usage_log: '&cUsage: /login <password>'
 wrong_pwd: '&cWrong password!'

src/test/resources/fr/xephi/authme/message/messages_test2.yml

@@ -1,6 +1,6 @@
 # Sample messages file
 
 unknown_user: 'Message from test2'
-unsafe_spawn: 'test2 - unsafe spawn'
+login: 'test2 - login'
 not_logged_in: 'test2 - not logged in'
 wrong_pwd: 'test2 - wrong password'