Added 4pcs and k-4pcs registration methods as proposed by Aiger et al. (2007) and Theiler et al. (2014)

Commit is together with fast transformation estimation to speed up the calculation using a minimum number of 3 points (planar case)
Added 4pcs and k-4pcs registration methods as proposed by Aiger et al. (2007) and Theiler et al. (2014)

Commit is together with fast transformation estimation to speed up the calculation using a minimum number of 3 points (planar case)