When Mojang added 1.13.2-pre2 to their manifest page it exposed a flaw
in the way the script's regex was getting the version json manifest.
I've tweaked the regex such that it will always first get the version
entry and then use that entry to get the json url, rather than trying to
do the whole thing in one shot.
Fixes GH-1582
ForgeFlower is better than Spigots FernFlower at decompiling the source.
However, in order to maintain the CraftBukkit patches, we must keep
using spigots for the primary.
However, for any file that we import on top of Spigots imported files
there is nothing stopping us from using better decompiled files.
So these changes will use ForgeFlower to maintain a better set of
decomped files, so anything we add on top of Paper can start off
in a better spot.
This is useful for project developers switching back and forth between
1.12.2 and 1.13 so we can have our IDE automatically use the
current version we are working on for included mc-dev files.
