* Update macOS PATH shenanigans.
c.f., https://github.com/koreader/koreader-base/pull/1052
* Prefer coreutils, it now ships everything we need.
(Or it always did? I apparently don't actually have coreutils
installed on my end).
* Also recommend putting Homebrew first in PATH
Mainly because it turns out that's how I tested this the last time ;).
Also, it just makes sense, and might be part of Homebrew's
recommendations anyway.
* Made Porting not so hilariously outdated.
* Minor tweaks to the macOS build instructions and the various quirks involved in getting it to behave (and accompanying actual build fixes).
This commit standardizes the various todos around the code a bit in a manner recognized by LDoc.
Besides drawing more attention by being displayed in the developer docs, they're also extractable with LDoc on the command line:
```sh
ldoc --tags todo,fixme *.lua
```
However, whether that particular usage offers any advantage over other search tools is questionable at best.
* and some random beautification