Added in -m option, seeks-per-second (version 2.05)

btt can now output data files containing seeks-per-second information.

---
 btt/args.c        |   17 +-
 btt/bt_timeline.c |    5 +-
 btt/doc/btt.tex   |   52 +-
 btt/doc/sps.eps   | 5377
+++++++++++++++++++++++++++++++++++++++++++++++++++++
 btt/globals.h     |    2 +-
 btt/seek.c        |   69 +-
 6 files changed, 5514 insertions(+), 8 deletions(-)