Add new built-in function type() that returns the name of the type of

the given value as a string. Includes test case.

src/main/java/lua/value/LThread.java

@@ -1,5 +1,10 @@
 package lua.value;
 
 public class LThread extends LValue {
+	public static final LString TYPE_NAME = new LString("thread");
+	
+	public LString luaGetType() {
+		return TYPE_NAME;
+	}
 
 }