The main motivation behind this is simplicity and correctnes, but the new small config library is also faster:
```
BenchmarkDefaultConfigProvider/Viper-16 252418 4546 ns/op 2720 B/op 30 allocs/op
BenchmarkDefaultConfigProvider/Custom-16 450756 2651 ns/op 1008 B/op 6 allocs/op
```
Fixes#8633Fixes#8618Fixes#8630
Updates #8591Closes#6680Closes#5192
- Add support for pretty urls [1]. Rewrite file links:
1. replace the `.org` extension with `/` (`/foo.org` -> `/foo/`)
2. prefix unrooted links with `../` as relative links start in the fake
subdirectory `/foo/` rather than `/`
- Fix case-sensitivity of org drawer `🔚`
[1] https://gohugo.io/content-management/urls/#pretty-urls
- Add support for #+MACRO
- fix a bug with #+LINK (edge case, should never happen anyways :TM:)
- Make title export optional (add export option)
- Remove cosmetic whitespace added by go-org (for easier visual
diffing) inside p tags (<p>\nfoo\n</p> => <p>foo</p>)
(should make `white-space: pre` on p look more in line with expectations)
- implement table separators via multiple tbodies (the html spec is ok with
that)
This commmit prepares for the addition of Goldmark as the new Markdown renderer in Hugo.
This introduces a new `markup` package with some common interfaces and each implementation in its own package.
See #5963
