* cargo fmt & clippy

* Skip anchor checking for URL with prefix in config

The access to translations is not straightforward and requires checks if
language and key exists. It is better to forbit direct access to
attribute and provide method - `get_translation()` - that will handle
all details of key translations.

Remove unit tests that use direct access and test only public method.

* 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

Add method get_translation(lang, key) into Config struct that retrieves
translated term from parsed configuration or error when either
desired language or key is missing.

Use the new method in Trans struct implementing global Tera function
trans().

Add unit test to cover both happy and error path for translation
retrieval in both config and templates crate.

>3.2.0 has an updated onig version which requires llvm
which isn't built in azure pipelines in Windows

Closes #726

* Add hard_link_static config option.

* Copy or hardlink file depending on an argument.

Modify the call sites for `copy_file` to account for the extra argument.

* Plug the config setting through to copy_file.

Don't apply the config option to theme's static directory.

* Update documentation.

* Backticks make no sense in this comment.

* Addressing PR comments.

* Be consistent with argument naming.

Closes #576

Closes #521

Closes #486

Switch to an `Option<usize>` for the serialized value of `rss_items`.
This lets us just set a blank value in the configuration and thereby
include *all* items.

This is a backwards-compatible change; it does not affect the behavior
of existing configurations.

Fixes #468. Closes #471.

Close #115

Closes #254

* Add ignored_content to the Config structure.
* Use the GlobSet crate to parse the glob patterns into a matcher, which
  is created once at program initialization. If there are no patterns in
  ignored_content, an empty globber is created, which excludes no files.
  This is consistent with the existing behaviour of Gutenberg, before
  this feature was added.
* Bail if there are any errors in the glob patterns.
* Add a call to the globber in page.rs to actually do the filtering.
* Update documentation.

A note on the Config structure
------------------------------
* I had to remove the PartialEq derive from the Config structure as it
  does not work for the GlobSet type. No harm is done, Config does not
  need to be PartialEq anyway, since there is no need to sort Configs.
* The implementation follows the pattern of the existing config settings
  in that it uses an Option<...>. This would appear unnecessary, in that
  an empty vec could be used as the default, but it appears to be needed
  by the TOML parsing. A better approach would be to use a separate
  SerializableConfig and map to/from a Config struct. This would also
  allow the elimination of most, if not all, of the other Options in
  the Config structure, but that ought to be another PR.

And fix bug with taxonomies urls

This removes the dependency cycle between config and rendering that
causes 4 packages to be recompiled every time a change is made.

I just want to code fast!

And some tweaks as I write the docs