IPEP 10: kernel side filtering of display formats

Draft implementation of [IPEP 10](https://github.com/ipython/ipython/wiki/IPEP-10:-kernel-side-filtering-of-display-formats)

This adds `active_types` list to DisplayFormatter as a global default for `include`,
rather than always having default of everything.

There is no change whatsoever for the default behavior of any zmq-based IPython kernels (notebook, qtconsole, etc.).
The only actual effect under default conditions is to eliminate the cost of registering unused formatters in terminal IPython.