Field handle lookup happens with every smart_ptr dereference

[lukehutch]

Currently Java field lookup happens on every smart pointer dereference in handle.h. This is slow, and only needs to be done once per class. The field reference can be held using a global reference:

http://journals.ecs.soton.ac.uk/java/tutorial/native1.1/implementing/refs.html

[m0glan]

Promise I'll look at all these in the weekend. If you have the time, please modify and creat pull requests accordingly

[lukehutch]

I have to figure out how to generate a PR from a cherry picked change, but the fix for this is here:

2b3995b

[gytwowo]

Did this need C++ library of pcl