big huge changes, so i dont remember everything.

* renaming, e.g. LU ---> FullPivLU
* split tests framework: more robust, e.g. dont generate empty tests if a number is skipped
* make all remaining tests use that splitting, as needed.
* Fix 4x4 inversion (see stable branch)
* Transform::inverse() and geo_transform test : adapt to new inverse() API, it was also trying to instantiate inverse() for 3x4 matrices.
* CMakeLists: more robust regexp to parse the version number
* misc fixes in unit tests

doc/snippets/Tutorial_solve_multiple_rhs.cpp

@@ -3,7 +3,7 @@ A << 1,2,3,  4,5,6,  7,8,10;
 Matrix<float,3,2> B;
 B << 3,1, 3,1, 4,1;
 Matrix<float,3,2> X;
-X = A.partialLu().solve(B);
+X = A.lu().solve(B);
 cout << "The solution with right-hand side (3,3,4) is:" << endl;
 cout << X.col(0) << endl;
 cout << "The solution with right-hand side (1,1,1) is:" << endl;