Launcher 2.1.519x

Changes

 * Fixed being able to resize the Launcher window to too small size on Mac and Linux.
 * Reduced the launcher update download size.
 * Enabled linux versions of the launcher beta.
 * Fixed linux versions showing update notifications despite no new versions being available.
 * Fixed the launcher crashing when reopened quickly after quitting.
 * Fixed being able to open duplicate instances of Minecraft without seeing a warning message.
 * Small layout and style fixes.
 * Updated translations.