Improve tessellation algorithm

Added new mesh class
Rewrite mesh algorithms to be less error prone
Make code more concise
Tried to add some documentation
Added half edge set

src/main/java/com/aaaaahhhhhhh/bananapuncher714/tess4j/HalfWing.java

@@ -1,5 +1,7 @@
 package com.aaaaahhhhhhh.bananapuncher714.tess4j;
 
+import com.aaaaahhhhhhh.bananapuncher714.mesh.Vector2d;
+
 public class HalfWing {
     protected HalfWing sym;
     protected HalfWing prev;