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/BirchFeature.cpp

@@ -42,7 +42,7 @@ bool BirchFeature::place(Level *level, Random *random, int x, int y, int z)
 	if ((belowTile != Tile::grass_Id && belowTile != Tile::dirt_Id) || y >= Level::maxBuildHeight - treeHeight - 1) return false;
 
 	// 4J Stu Added to stop tree features generating areas previously place by game rule generation
-	if(app.getLevelGenerationOptions() != NULL)
+	if(app.getLevelGenerationOptions() != nullptr)
 	{
 		LevelGenerationOptions *levelGenOptions = app.getLevelGenerationOptions();
 		int radius = 3;