[global] Restyle the outer frame

Change the following

• remove the top bar
• restyle the perspective bar
• move the spinner
• move logout from top bar to left
• move auto-export from top bar to left

Q&A:
Q: which technology do we use for the perspective icons?
A: .svg icon files, with a dedicated .svg per rendered size (to enable to use of sharp, really thin lines in larger icons), and a separate file per icon "state" (e.g. a separate .svg icon for the 'active' state of perspectives)