Fixed divison by zero in the computation of a direction vector in ccd…

…MPRPenetration. (fixes danfis#49)

In some cases, a touching contact is found in the findPenetr function. In this
case the direction vector is set to (0, 0, 0).

libccd v2.0

libccd v1.5

libccd v1.4

libccd v1.3

libccd v1.2

libccd v1.1

libccd v1.0

libgjk v0.2

libgjk v0.1