Update readme.rst

Add registration support note to README
Merge pull request #48 from jabooth/patch-1

Update README to mention ICP support
fix failing tests

... by just changing the numbers.
Fix kdtree example
get sensor origin and orientation from PointCloud
Merge pull request #54 from larsmans/fix-tests

Fix failing tests
Merge pull request #55 from larsmans/fix-kdtree

Fix kdtree example
Merge pull request #56 from larsmans/sensor-info

get sensor origin and orientation from PointCloud
stop copying point clouds around

Changes the PointCloud object layout to store a shared_ptr. This
actually simplifies quite a bit of the code (fewer casts), at the
expense of a hack to assign to a shared_ptr and a Cython 0.21
requirement.
refactor registration and run algorithms without the GIL
copy constructor for point clouds