luamin preserve title and author comments
If a PICO-8 cart's Lua code has two line comments at the top of its source code, it uses them as the text for the title and author lines when generating a cart label. luamin currently strips all comments. It should detect the title and author comments and preserve them in the minified output if present.

Inspired by [PR 54](https://github.com/dansanderson/picotool/pull/54/files), though that isn't a complete implementation: it is using the first two comments regardless of where they appear. It should only use the first two comments that appear before any other source.