* big rework of Inverse.h:

- remove all invertibility checking, will be redundant with LU
  - general case: adapt to matrix storage order for better perf
  - size 4 case: handle corner cases without falling back to gen case.
  - rationalize with selectors instead of compile time if
  - add C-style computeInverse()
* update inverse test.
* in snippets, default cout precision to 3 decimal places
* add some cmake module from kdelibs to support btl with cmake 2.4

Eigen/src/Core/MatrixBase.h

@@ -516,8 +516,8 @@ template<typename Derived> class MatrixBase
 
 /////////// LU module ///////////
 
-    const Inverse<typename ei_eval<Derived>::type, true> inverse() const;
-    const Inverse<typename ei_eval<Derived>::type, false> quickInverse() const;
+    const typename ei_eval<Derived>::type inverse() const;
+    void computeInverse(typename ei_eval<Derived>::type *result) const;
     Scalar determinant() const;