Add submodules and build scripts

These will be made default in 1.9, dropping PaperTools support

decompile.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+PS1="$"
+basedir=`pwd`
+workdir=$basedir/work
+minecraftversion=$(cat BuildData/info.json | grep minecraftVersion | cut -d '"' -f 4)
+decompiledir=$workdir/$minecraftversion
+classdir=$decompiledir/classes
+
+echo "Extracting NMS classes..."
+if [ ! -d "$classdir" ]; then
+    mkdir -p "$classdir"
+    cd "$classdir"
+    jar xf "$decompiledir/$minecraftversion-mapped.jar" net/minecraft/server
+    if [ "$?" != "0" ]; then
+        cd "$basedir"
+        echo "Failed to extract NMS classes."
+        exit 1
+    fi
+fi
+
+echo "Decompiling classes..."
+if [ ! -d "$decompiledir/net/minecraft/server" ]; then
+    cd "$basedir"
+    java -jar BuildData/bin/fernflower.jar -dgs=1 -hdc=0 -rbr=0 -asc=1 -udv=0 "$classdir" "$decompiledir"
+    if [ "$?" != "0" ]; then
+        echo "Failed to decompile classes."
+        exit 1
+    fi
+fi