This relates to #3123.
The interfaces and types in `target` made sense at some point, but now this package is too restricted to a hardcoded set of media types.
The overall current logic:
* Create a file path based on some `Translator` with some hardcoded logic handling uglyURLs, hardcoded html suffix etc.
* In in some cases (alias), a template is applied to create the alias file.
* Then the content is written to destination.
One could argue that it is the last bullet that is the actual core responsibility.
This commit fixes that by moving the `hugolib`-related logic where it belong, and simplify the code, i.e. remove the abstractions.
This code will most certainly evolve once we start on #3123, but now it is at least possible to understand where to start.
Fixes#3123
This commit makes sure that the `.Site.LastChange` is fetched from the latest page modification date.
Previously, this value was fetched from the last page in the default page sort, which may not be the last by date
if weight is set.
Fixes#2909Closes#2910
Note that this looks like overkill for just the logger, and that is correct,
but this will make sense once we start with the template handling etc.
Updates #2701
This includes removing the error return value from Permalink and RelPermalink.
We ignore that error all over the place, so we might as well remove it.
Updates #2297
To make it easier to follow and understand.
Both building and rebuilding now follow a four step flow:
1. Init
2. Process
3. Assemble
4. Render
And now there are only one Build method, used for both builds and rebuilds.
Updates #2297
