Fixed a few regressions related to the recent command refactoring.

• New: Added support for hierarchical/nested tags (#2572 by Vaidotas Šimkus)
  
• Fixed: Fix filename when exporting notebook as Markdown (#3473)
  
• Fixed: Fixed alarms on macOS
  
• Fixed: Improve Markdown rendering in CodeMirror, in particular for math expressions (#3448) (#3440 by @CalebJohn)
  
• Fixed: Crash when applying tags to multiple notes from within another tag (#3481)
  
• Fixed: Fixed regression when moving note to notebook from menu (#3482)