[ODE] Box/Trimesh contact filtering and oblong geoms

[Tyler Streeter]

Rather than use an absolute epsilon, would it be better to use the
combined absolute and relative tolerance method mention in Christer
Ericson's talk?  Here's how I implemented it:

	/// Returns true if the two values are equal within some tolerance, 
	/// using a combination of absolute and relative (epsilon is scaled 
	/// by the magnitudes of the values) tolerance, depending on whether 
	/// both values are both less than 1.
	/// See Christer Ericson's GDC 2005 presentation: 
	/// http://realtimecollisiondetection.net/pubs/GDC05_Ericson_Numerical_Robustness_for_Geometric_Calculations.ppt
	inline bool areEqual(real x, real y)
	{
		real maxVal = 1;

		if (abs(x) > maxVal)
		{
			maxVal = abs(x);
		}

		if (abs(y) > maxVal)
		{
			maxVal = abs(y);
		}

		if (abs(x - y) <= EPSILON * maxVal)
		{
			return true;
		}
		else
		{
			return false;
		}
	}