Evening commit.
Merge branch 'master' of https://github.com/Isaisaisa/DB-Merlin
updated AES module. Fixed bug, where decrypted string still contained zero byte chars.

Application.java: Added hashtable for default values of all properties. Added methods to ensure properties consistency (no null values / references!)
Properties are now saved on shutdown() by default. Can be altered by calling shutdown(false);
getLogin() now returns an array of {"", ""}, if LoginData are invalid instead of returning null references to non existent values.
Added getDbUsername() and getDbPassword() for comfortable getting of login data for the DatabaseSetup GUI.
Added  general closeMerlinYesNo() prompt.
Major fix to DatabaseSetup GUI. Login works from now on. Login data CANNOT be remembered yet.
DatabaseSetup and MerlinLogin now do auto-center on startup.
Added WindowListers to react on closing calls and stuff.
MerlinLogic.java: Added multiple validation checking methods for specific inputs like username, password, email, e.g. ONLY CHECKS IF STRINGS ARE EMPTY ATM. NO FURTHER CHECKINGS.
                  Added methods for login to merlin (NOT FINISHED YET) and database (DONE). They're for access from GUIs. Any checkings neccessary are being triggered and evaluated by them without the need for manual triggered methods by the user after triggering these methods to accomplish the login.

Added constant keys.

.gitignore update specificly.
updated config.properties.