Do not use namespace Eigen and KDL for Orocos types

[meyerj]

From #26 (comment):

But the VectorTypeInfo<T> and related functions should not be exposed as part of the Eigen namespace and deserve their own namespace eigen_typekit or similar instead. There might be some difficulties related to argument depending lookup. For example, the istream streaming operators should be defined in the RTT::types namespace so that they will be found by the implementation of TypeStreamSelector without having to "pollute" the Eigen namespace. An alternative to define streaming operators is to specialize this template class for Eigen types and don't use the streaming operators at all.