Support Travis CI testing

more efficient vector rotation without explicitly assigning quaternions

Fix bug in capsule support function

  one is working, the other one fails to compute the nearest points although
  it properly computes the distance.

  - do not assume that input vector dir is normalized.

Add a test on distance computation between capsule and box.

  - test fails on current version.

fixed wrong call of projectInTriangle()

Add a few methods in Matrix3fX and Vec3fX:

  Matrix3fX::isIdentity,
  Vec3fX::norm, Vec3fX::squaredNorm,
  Vec3fX::setZero,
  operator * (double, Vec3fX).x

Check that quaternion is normalized when converting to rotation matrix

  The conversion formula used is valid only for unit quaternions.
  If a user passes a zero quaternion by mistake, the resulting matrix is
  identity. This is very confusing since multiplying by a Transform3f containing
  0 as a quaternion results in identity Transform3f.

extending capsule-capsule distance computation

  adding a test.

Add an accessor to shared pointer to CollisionGeometry member.