[ 1691402 ] Heighfield performance patch patch
[ 1691402 ] Heighfield performance patch patch

Fix two bug introduced in last patch and reported in mailing list :

- Ray segfault on tagential cases
- XZ oriented terrain that was letting object falling through and made the
reporter uses previous implementation.
keletskiy/ode,nabijaczleweli/ODE,keletskiy/ode,nabijaczleweli/ODE,nabijaczleweli/ODE,keletskiy/ode,keletskiy/ode,nabijaczleweli/ODE,nabijaczleweli/ODE,nabijaczleweli/ODE,keletskiy/ode,keletskiy/ode