ikiwiki/ ikiwiki/ pagespec/ sorting

Some directives that use PageSpecs allow specifying the order that matching pages are shown in. The following sort orders can be specified using the `sort` parameter:

- `age` - List pages from the most recently created to the oldest.

- `mtime` - List pages with the most recently modified first.

- `title` - Order by title (page name), e.g. "z/a a/b a/c"

- `path` - Order by page name including parents, e.g. "a/b a/c z/a"

- `meta(title)` - Order according to the `[[!meta title="foo" sortas="bar"]]` or `[[!meta title="foo"]]` directive, or the page name if no full title was set. `meta(author)`, `meta(date)`, `meta(updated)`, etc. also work.

In addition, you can combine several sort orders and/or reverse the order of sorting, with a string like `age -title` (which would sort by age, then by title in reverse order if two pages have the same age).