v0.2.5

1. Support syntax highlighting for *.rzk.tex files (see #5).
2. Add icons for literate Rzk files (both Markdown and TeX, see #13).
3. Some minor fixes (restoring rainbow-parentheses and keybinding for code commenting).
4. Using YAML for the language grammar (see #6).
5. Add launch.json and prettify (see #1)