docs: Document permalinks
Add dir and page functions and fix partial function
templates: Return error from LoadTemplate
funcs: Add reverse
dir: Sort by weight, date, and filepath
Add FilePath and Weight field to pages
dir: Fix assignment of Prev field
Fix index page paths
Use _index for index pages

Pages with the name "index" will use the page template, and pages with
the name "_index" will use the index template.
page: Add Prev and Next fields
templates: Parse all templates in the directory

To allow for specifying custom templates in frontmatter in the future.
kiln new: Create public directory
docs: Remove link to TOML website
Update example site configuration
Update documentation
Move templates to templates/_default
Move funcs to funcs.go
Add strings.Join function
Add string functions for use in templates
Update documentation
Allow multiple input formats per task