1) Set them to the values that (according to Rob) avoided performance
   regressions.  This means that the scheduler won't get much exercise
   until we implement KIST or something like it.

2) Rename the options to end with a __, since I think they might be
   going away, and nobody should mess with them.

3) Use the correct types for the option variables. MEMUNIT needs to be a
   uint64_t; UINT needs to be (I know, I know!) an int.

4) Validate the values in options_validate(); do the switch in
   options_act(). This way, setting the option to an invalid value on
   a running Tor will get backed out.