Create a symlink on not-windows to current minecraft decompile dir

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.

scripts/decompile.sh

@@ -6,9 +6,9 @@ PS1="$"
 basedir="$(cd "$1" && pwd -P)"
 workdir="$basedir/work"
 minecraftversion=$(cat "$workdir/BuildData/info.json"  | grep minecraftVersion | cut -d '"' -f 4)
+windows="$([[ "$OSTYPE" == "cygwin" || "$OSTYPE" == "msys" ]] && echo "true" || echo "false")"
 decompiledir="$workdir/Minecraft/$minecraftversion"
 classdir="$decompiledir/classes"
-
 echo "Extracting NMS classes..."
 if [ ! -d "$classdir" ]; then
     mkdir -p "$classdir"
@@ -30,4 +30,13 @@ if [ ! -d "$decompiledir/net/minecraft/server" ]; then
         exit 1
     fi
 fi
+
+# set a symlink to current
+currentlink="$workdir/Minecraft/current"
+if ([ ! -e "$currentlink" ] || [ -L "$currentlink" ]) && [ "$windows" == "false" ]; then
+	echo "Pointing $currentlink to $minecraftversion"
+	rm -rf "$currentlink"
+	ln -sfn "$minecraftversion" "$currentlink"
+fi
+
 )