Tray icon and console window stay after relaunching

[MJRamon]

Each new launch of the modpack will create new and new tray icon and console window.

Steps to reproduce: launch a modpack, exit, repeat. Get unlimited console windows.

Expected behavior: console window should clear itself and start printing fresh information / launcher should close old one and start a new one.

Instead, player has to close a console window each new launch. Setting consoleFrame.setVisible(false); in LaunchProcessHandler.java leads to similar problem - tray icons pile up.

[hedgehog1029]

The current behavior is intentional but I may consider changing it.