Project modernization (#630)

* Fixed boats falling and a TP glitch #266

* Replaced every C-style cast with C++ ones

* Replaced every C-style cast with C++ ones

* Fixed boats falling and a TP glitch #266

* Updated NULL to nullptr and fixing some type issues

* Modernized and fixed a few bugs

- Replaced most instances of `NULL` with `nullptr`.
- Replaced most `shared_ptr(new ...)` with `make_shared`.
- Removed the `nullptr` macro as it was interfering with the actual nullptr keyword in some instances.

* Fixing more conflicts

* Replace int loops with size_t and start work on overrides

Minecraft.World/WaterLevelChunk.cpp

@@ -160,5 +160,5 @@ void WaterLevelChunk::setLevelChunkBrightness(LightLayer::variety layer, int x,
 
 Biome *WaterLevelChunk::getBiome(int x, int z, BiomeSource *biomeSource)
 {
-	return NULL;
+	return nullptr;
 }