router: store servers in a pool such that we reuse identical ones
router: store servers in a pool such that we reuse identical ones

This is roughly the fix for issue #150, but needs refinement (issue #156
and #157) to function properly.

piotr1212/carbon-c-relay,piotr1212/carbon-c-relay,grobian/carbon-c-relay,grobian/carbon-c-relay,grobian/carbon-c-relay,piotr1212/carbon-c-relay,piotr1212/carbon-c-relay