[FEATURE] New Home Screen

[ma7t3]

The current startup dialog should be replaced with a new full window home screen as a dock instead of a dialog.
The idea is, to set it up similar to the Qt Creator home screen, it should contain:

• basic options, the current dialog has as well, like:
  • Create new project (empty, project wizard (not existing for now) or import)
  • Open any project from file
  • preferences
  • help/manual
  • maybe UI tour
  • exit
• last used file list (better than the current one including icon, proper project name, last used etc.)
• notifications/messages panel with the following message types:
  • welcome-message (if someone just installed ScheduleMaster)
  • update messages (before update like "there is an update available, click here to instal")
  • messages after succesful update ("welcom back", changelog)
  • custom messages (download from the web, like big feature announcements and other stuff)
  • ...