[foxtrot] PollardRho msgs

[M. Shreeve]

Hi Everyone (sorry Mat, Idriss, this probably doesn't concern you :)

At the moment PollardRhoWorkUnit prints out lots (and lots) of stuff when
running in the debug log level.  When running in the all msgs mode it
prints nothing.  Please could there be a compromise here, eg have an
interesting msg to be that a WorkUnit has been received/returned, debug to
include some mathy stuff, but not thousands of lines !

Cheers,

m = 201
m >= 3*n/2
xN = 139448249971509254391721276533594126
xM = 1418717557018205175888126714643645887
xM = 1053151540414518475575290273865610498
m = 202
m >= 3*n/2
xN = 139448249971509254391721276533594126
xM = 1053151540414518475575290273865610498
xM = 639246843918223996262058527397591616
m = 203
m >= 3*n/2
xN = 139448249971509254391721276533594126
xM = 639246843918223996262058527397591616
xM = 661777027661821486427757757011164712
m = 204
m >= 3*n/2
xN = 139448249971509254391721276533594126
xM = 661777027661821486427757757011164712
xM = 612744797586798838009391080365246732

ad (nearly) infinitum  :)