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.Client/MobSkinTextureProcessor.cpp

@@ -3,14 +3,14 @@
 
 BufferedImage *MobSkinTextureProcessor::process(BufferedImage *in)
 {
-    if (in == NULL) return NULL;
+    if (in == nullptr) return nullptr;
 
     width = 64;
     height = 32;
 
     BufferedImage *out = new BufferedImage(width, height, BufferedImage::TYPE_INT_ARGB);
     Graphics *g = out->getGraphics();
-    g->drawImage(in, 0, 0, NULL);
+    g->drawImage(in, 0, 0, nullptr);
     g->dispose();
 
     pixels = out->getData();