Chai cVector cMatrix Eigen Conversion

[geraldb]

We should have functions to convert from Eigen to Chai data types instead of 100 x

Eigen::Vector3d& tmp_ref = db_->s_gui_.ui_point_[it->ui_pt_];
it->chai_pos_des_->setLocalPos(tmp_ref(0),tmp_ref(1),tmp_ref(2));

this would make the code a lot cleaner

[Samir Menon]

Chai still has eigen support. It's a bit buggy for now. You can re-enable it by setting C_USE_EIGEN in the compiler flags. I'm not using that setting as a default till the chai version stabilizes.

[Samir Menon]

Issue #51 was marked as a duplicate of this issue.

[Samir Menon]

Chai's Eigen support is inconsistent. We'll stick with this.