message: fix lispsm when camera and light direction are aligned
  in that case we have to revert to the ortho projection
diff: @@ -511,7 +511,8 @@ mat4f ShadowMap::applyLISPSM(mat4f& Wp,
  mat4f W;
  // see nopt1 below for an explanation about this test
  // sinLV is positive since it comes from a square-root
  - if (sinLV > 0 && 3.0f * (dzn / (zf - zn)) < 2.0f) {
  + constexpr float epsilon = 0.02f; // very roughly 1 degree
  + if (sinLV > epsilon && 3.0f * (dzn / (zf - zn)) < 2.0f) {
  // nopt is the optimal near plane distance of Wp (i.e. distance from P).
  // virtual near and far planes
  