jet engine removal

• latest important update: v0.11.20 (but skip right to this version)
• latest gzip edition of the sfx: v0.11.18
• if upgrading from v0.11.x or before, see v0.12.4

new features

• toggle file-selection in the image viewer with hotkey s or using the sel button

bugfixes

• chrome would max a cpu core (and consume even more ram than usual) after sitting idle in the browser for a few weeks due to recursive setTimeouts
  • just the setTimeout call itself took like 67 msec seriously
  • (firefox was completely fine)
• button placement in huge modals
• play videos in the gallery when clicked
• cut/paste files on ancient chrome versions