Created NBT stream API (markdown)

NBT-stream-API.md

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+With FAWE you can stream a schematic, or any NBT stream without having to store the whole thing into memory.
+ - You have to do this if a file is too large to fit in memory
+ - Or if you just want to obtain some information from the stream
+
+```Java
+// Let's stream some info from a schematic file without having to load the whole thing into memory
+// Schematics are compressed, so we need to use a GZIPInputStream before the NBTInputStream
+File file = new File("blah.schematic");
+NBTInputStream is = new NBTInputStream(new GZIPInputStream(new FileInputStream(file)));
+NBTStreamer streamer = new NBTStreamer(is);
+
+// Get the height,width,length
+final Map<String, Short> dimensions = new HashMap<>();
+// You need to know the structure of the NBT file, these specific values are all shorts
+streamer.addReader(new NBTStreamer.NBTStreamReader<Integer, Short>() {
+    @Override
+    public void run(Integer index, Short value) {
+        // The index is unimportant for this, but for Lists, or Arrays it might be useful
+        dimensions.put(getNode(), value); // Put e.g. Schematic.Width -> 53
+    }
+}, "Schematic.Width", "Schematic.Height", "Schematic.Length");
+
+// Let's get the Entities, I know that they will be of type CompoundTag
+streamer.addReader("Schematic.Entities.#", new NBTStreamer.NBTStreamReader<Integer, CompoundTag>() {
+    @Override
+    public void run(Integer index, CompoundTag entity) {
+        // For the .# and normal readers, it will always be Index, Value
+        // Here we can do something with each entitiy
+    }
+});
+
+// Get some info about the Blocks section (which contains the ids) (there's also AddBlocks, and Data)
+streamer.addReader("Schematic.Blocks.?", new NBTStreamer.NBTStreamReader<Integer, Integer>() {
+    @Override
+    public void run(Integer length, Integer type) {
+        Class<? extends Tag> clazz = NBTConstants.getClassFromType(type);
+        // Here we can do something knowing the length of the section and its type
+    }
+});
+
+// Now that we have the readers we want, we can read through the file
+streamer.readFully();
+System.out.println("Dimensions are: " + dimensions);
+```
+See: https://github.com/boy0001/FastAsyncWorldedit/blob/master/core/src/main/java/com/boydti/fawe/jnbt/SchematicStreamer.java