2 - Authorities now assign the Guard flag to the fastest 25% of the
3 network (it used to be the fastest 50%). Also raise the consensus
4 weight that guarantees the Guard flag from 250 to 2000. For the
5 current network, this results in about 1100 guards, down from 2500.
6 This step paves the way for moving the number of entry guards
7 down to 1 (proposal 236) while still providing reasonable expected
8 performance for most users. Implements ticket 12690.