Move other lone thirdparty files to thirdparty/misc

Also move Box2D ConvexDecomposition contrib code to
thirdparty/b2d_convexdecomp.

thirdparty/b2d_convexdecomp/b2Triangle.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2007 Eric Jordan
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ * 1. The origin of this software must not be misrepresented; you must not
+ * claim that you wrote the original software. If you use this software
+ * in a product, an acknowledgment in the product documentation would be
+ * appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ * misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+#ifndef B2_TRIANGLE_H
+#define B2_TRIANGLE_H
+
+#include "b2Glue.h"
+
+namespace b2ConvexDecomp {
+
+
+
+class b2Triangle{
+public:
+	float* x;
+    float* y;
+	b2Triangle();
+	b2Triangle(float32 x1, float32 y1, float32 x2, float32 y2, float32 x3, float32 y3);
+	~b2Triangle();
+	bool IsInside(float32 _x, float32 _y);
+	void Set(const b2Triangle& toMe);
+
+};
+
+}
+#endif