and rm the old ones

changes/bug4489

-  o Major bugfixes (performance):
-    - Remove the artificially low cutoff of 20KB to guarantee the Fast
-      flag. In the past few years the average relay speed has picked
-      up, and while the "top 7/8 of the network get the Fast flag" and
-      "all relays with 20KB or more of capacity get the Fast flag" rules
-      used to have the same result, now the top 7/8 of the network has
-      a capacity more like 32KB. Bugfix on 0.2.1.14-rc. Fixes bug 4489.
-

changes/bug4518

-  o Minor bugfixes (performance):
-    - Avoid frequent calls to the fairly expensive cull_wedged_cpuworkers
-      function. This was eating up hideously large amounts of time on some
-      busy servers. Fixes bug 4518.

changes/feature4484

-  o Minor features:
-    - Add two new config options for directory authorities:
-      AuthDirFastGuarantee sets a bandwidth threshold for guaranteeing the
-      Fast flag, and AuthDirGuardBWGuarantee sets a bandwidth threshold
-      that is always sufficient to satisfy the bandwidth requirement for
-      the Guard flag. Now it will be easier for researchers to simulate
-      Tor networks with different values. Resolves ticket 4484.
-