* maybe_slugify() only does simple sanitation if config.slugify is false

* slugify is disabled by default, turn on for backwards-compatibility

* First docs changes for optional slugification

* Remove # from slugs but not &

* Add/fix tests for utf8 slugs

* Fix test sites for i18n slugs

* fix templates tests for i18n slugs

* Rename slugify setting to slugify_paths

* Default slugify_paths

* Update documentation for slugify_paths

* quasi_slugify removes ?, /, # and newlines

* Remove forbidden NTFS chars in quasi_slugify()

* Slugification forbidden chars can be configured

* Remove trailing dot/space in quasi_slugify

* Fix NTFS path sanitation

* Revert configurable slugification charset

* Remove \r for windows newlines and \t tabulations in quasi_slugify()

* Update docs for output paths

* Replace slugify with slugify_paths

* Fix test

* Default to not slugifying

* Move slugs utils to utils crate

* Use slugify_paths for anchors as well

* Update installation.md

* Update cli-usage.md

* Update installation.md

* Update directory-structure.md

* Update configuration.md

* Update overview.md

* Update section.md

* Update page.md

* Update section.md

* Update configuration.md

* Update page.md

* Update section.md

* Update page.md

* Update shortcodes.md

* Update linking.md

* Update table-of-contents.md

* Update syntax-highlighting.md

* Update taxonomies.md

* Update search.md

* Update sass.md

* Update index.md

* Update multilingual.md

* Update overview.md

* Update pages-sections.md

* Update pagination.md

* Update taxonomies.md

* Update rss.md

* Update sitemap.md

* Update robots.md

* Update 404.md

* Update archive.md

* Update overview.md

* Update installing-and-using-themes.md

* Update creating-a-theme.md

* Update netlify.md

* Update github-pages.md

* Update gitlab-pages.md

* Update index.md

* Update page.md

* Update section.md

* Updates.

* Let toc is visable through Page & Section variables in templates

* Removed the current toc variable from page & section

- "/templates" section is gone upstream

* fix the issue of generating the search index for multiple language

* updat docs for generating the search index for multiple language

* fix failed tests

* add tests for the search index of multiple language

Closes #790

Closes #727

Close #686

Justification for this feature is added in the docs.

Precedent for the precise syntax: Hugo.

Hugo puts this syntax behind a preference named headerIds, and automatic
header ID generation behind a preference named autoHeaderIds, with both
enabled by default. I have not implemented a switch to disable this.

My suggestion for a workaround for the improbable case of desiring a
literal “{#…}” at the end of a header is to replace `}` with `}`.

The algorithm I have used is not identical to [that
which Hugo uses][0], because Hugo’s looks to work at the source level,
whereas here we work at the pulldown-cmark event level, which is
generally more sane, but potentially limiting for extremely esoteric
IDs.

Practical differences in implementation from Hugo (based purely on
reading [blackfriday’s implementation][0], not actually trying it):

- I believe Hugo would treat `# Foo {#*bar*}` as a heading with text
  “Foo” and ID `*bar*`, since it is working at the source level; whereas
  this code turns it into a heading with HTML `Foo {#<em>bar</em>}`, as
  it works at the pulldown-cmark event level and doesn’t go out of its
  way to make that work (I’m not familiar with pulldown-cmark, but I get
  the impression that you could make it work Hugo’s way on this point).
  The difference should be negligible: only *very* esoteric hashes would
  include magic Markdown characters.

- Hugo will automatically generate an ID for `{#}`, whereas what I’ve
  coded here will yield a blank ID instead (which feels more correct to
  me—`None` versus `Some("")`, and all that).

In practice the results should be identical.

Fixes #433.

[0]: a477dd1646/block.go (L218-L234)

Fix #613

Closes #537

To override all child pages

Closes #397
Tests from PR #434

Closes #413
Closes #408

Fix #396

Fix #490

Closes #485

Fix #122

Also fix tests

Close #367, #372