* Implement `hx --tutor` and `:tutor` to load `tutor.txt`
* Document `hx --tutor` and `:tutor`
* Change `Document::set_path` to take an `Option`
* `Document::set_path` accepts an `Option<&Path>` instead of `&Path`.
* Remove `Editor::open_tutor` and make tutor-open functionality use
`Editor::open` and `Document::set_path`.
* Use `PathBuf::join`
Co-authored-by: Ivan Tham <pickfire@riseup.net>
* Add comments explaining unsetting tutor path
Co-authored-by: Ivan Tham <pickfire@riseup.net>
* Add preview pane for fuzzy finder
* Fix picker preview lag by caching
* Add picker preview for document symbols
* Cache picker preview per document instead of view
* Use line instead of range for preview doc
* Add picker preview for buffer picker
* Fix render bug and refactor picker
* Refactor picker preview rendering
* Split picker and preview and compose
The current selected item is cloned on every event, which is
undesirable
* Refactor out clones in previewed picker
* Retrieve doc from editor if possible in filepicker
* Disable syntax highlight for picker preview
Files already loaded in memory have syntax highlighting enabled
* Ignore directory symlinks in file picker
* Cleanup unnecessary pubs and derives
* Remove unnecessary highlight from file picker
* Reorganize buffer rendering
* Use normal picker for code actions
* Remove unnecessary generics and trait impls
* Remove prepare_for_render and make render mutable
* Skip picker preview if screen small, less padding
Fixes#378. The issue was that because indent style detection
ran before language detection, there was no language indent
style to fall back on if indent style detection failed, so it
would just default to 2 spaces.