The old implementation had some issues, mostly related to the context (e.g. name, file paths) passed to the template.
This new implementation is using the exact same code path for evaluating the pages as in a regular build.
This also makes it more robust and easier to reason about in a multilingual setup.
Now, if you are explicit about the target path, Hugo will now always pick the correct mount and language:
```bash
hugo new content/en/posts/my-first-post.md
```
Fixes #9032
Fixes #7589
Fixes #9043
Fixes #9046
Fixes #9047
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 #8633
Fixes #8618
Fixes #8630
Updates #8591
Closes #6680
Closes #5192
Many users seem to stumble over creating new sites in existing non-empty directories. And that `--force` is the necessary option. So I added *See --force* as a hint to the error.
Fixes #4825.
The main item in this commit is showing of errors with a file context when running `hugo server`.
This can be turned off: `hugo server --disableBrowserError` (can also be set in `config.toml`).
But to get there, the error handling in Hugo needed a revision. There are some items left TODO for commits soon to follow, most notable errors in content and config files.
Fixes #5284
Fixes #5290
See #5325
See #5324
