python3-imaging doesn't exist but python3-pil does, which
python3-pillow is aliased to. It also includes the necessary headers.
Add a note about pip missing the headers and warn of ABI mismatches if
people do weird things.
I've had to fight rst a lot to get this right, somehow the code
block after the last bullet point breaks if you explicitly number
the enumerated list instead of using auto-enumeration. Like legit,
change `#.` to `12.` and it'll break. No clue why.
I've adjusted the macOS instructions slightly to be more general,
e.g. do not advise symlinking a specific Python executable of a
specific version, just tell people they should make sure it's in
their environment.
And yes, on Windows, python.exe is whatever version you have installed,
so if you install Python 3, python.exe is going to be Python 3.
I've removed the FreeBSD instructions because they only talk about
working around ports potentially using Python 2.6, which is no longer
relevant. If somebody here uses FreeBSD and has anything to add to the
instructions not already covered by the Linux instructions, let me know.
Updates to the Windows build instructions, terminology pulled from the current "Visual Studio Community 2017" version, which is the free version of VS at this time. I wrote these as a first timer building Overviewer. I also moved all of the pre-requisites to a bulleted list under a single header.
It's EOL in a few days and the instructions only add confusion.
Anyone still using CentOS 5 has bigger issues than not having
documentation on how to build Minecraft-Overviewer.
