This commit adds support for a configuration directory (default `config`). The different pieces in this puzzle are:
* A new `--environment` (or `-e`) flag. This can also be set with the `HUGO_ENVIRONMENT` OS environment variable. The value for `environment` defaults to `production` when running `hugo` and `development` when running `hugo server`. You can set it to any value you want (e.g. `hugo server -e "Sensible Environment"`), but as it is used to load configuration from the file system, the letter case may be important. You can get this value in your templates with `{{ hugo.Environment }}`.
* A new `--configDir` flag (defaults to `config` below your project). This can also be set with `HUGO_CONFIGDIR` OS environment variable.
If the `configDir` exists, the configuration files will be read and merged on top of each other from left to right; the right-most value will win on duplicates.
Given the example tree below:
If `environment` is `production`, the left-most `config.toml` would be the one directly below the project (this can now be omitted if you want), and then `_default/config.toml` and finally `production/config.toml`. And since these will be merged, you can just provide the environment specific configuration setting in you production config, e.g. `enableGitInfo = true`. The order within the directories will be lexical (`config.toml` and then `params.toml`).
```bash
config
├── _default
│ ├── config.toml
│ ├── languages.toml
│ ├── menus
│ │ ├── menus.en.toml
│ │ └── menus.zh.toml
│ └── params.toml
├── development
│ └── params.toml
└── production
├── config.toml
└── params.toml
```
Some configuration maps support the language code in the filename (e.g. `menus.en.toml`): `menus` (`menu` also works) and `params`.
Also note that the only folders with "a meaning" in the above listing is the top level directories below `config`. The `menus` sub folder is just added for better organization.
We use `TOML` in the example above, but Hugo also supports `JSON` and `YAML` as configuration formats. These can be mixed.
Fixes#5422
This means that the current `.Site` and ´.Hugo` is available as a globals, so you can do `site.IsServer`, `hugo.Version` etc.
Fixes#5470Fixes#5467Fixes#5503
When the page parser was rewritten in 0.51, this was interpreted literally, but commented out front matter is used in the wild to "hide it from GitHub", e.g:
```
<!--
+++
title = "hello"
+++
-->
```
Fixes#5478
An inline shortcode's name must end with `.inline`, all lowercase.
E.g.:
```bash
{{< time.inline >}}{{ now }}{{< /time.inline >}}
```
The above will print the current date and time.
Note that an inline shortcode's inner content is parsed and executed as a Go text template with the same context as a regular shortcode template.
This means that the current page can be accessed via `.Page.Title` etc. This also means that there are no concept of "nested inline shortcodes".
The same inline shortcode can be reused later in the same content file, with different params if needed, using the self-closing syntax:
```
{{< time.inline />}}
```
Fixes#4011
In the newly consolidated file cache implementation, we forgot that we also look in the theme(s) for assets (SCSS transformations etc.), which is not good for Netlify and the demo sites.
Fixes#5460
