New features

• Add support for all of bat's code highlighting themes (#67).
• Add terminal-dark and terminal-light themes that preserve the terminal's colors and background (#68 #69).
• Allow placing themes in $HOME/.config/presenterm/themes to make them available automatically as if they were
  built-in themes (#73).
• Allow configuring the default theme in $HOME/.config/presenterm/config.yaml (#74).
• Add support for rendering LaTeX and typst code blocks automatically as images (#75 #76 #79 #81).
• Add syntax highlighting support for nix and diff (#78 #82) (thanks @GaetanLepage and @rmartine-ias)
• Add comment command to jump into the middle of a slide (#86).
• Add configuration option to have implicit slide ends (#87 #89).
• Add configuration option to have custom comment-command prefix (#91).