Instead of deleting hardcoded commands in filterHistory, sort commands
by usage and let the user select in fzf. If fzf is not installed, show
the most used ones and let the user select manually.
Keep the first occurence in the history for stuff like autosuggestions.
Add existence check for given file. (How did I forget that?)
Create automatic backup in temporary directory and use it to show
overview of deleted commands.
Make sed expression more readable by using double quotes for the whole
regex and escaping the $ instead of a mix between single and double.
