Mostly verbosity changes.

GONE AWAY:  -dshow-passes, -ddump-all, -ddump-most.

NEW:
    -v<n>, where <n> is

    0	|   print errors & warnings only
    1   |   minimal verbosity: print "compiling M ... done." for each module.
    2   |   equivalent to -dshow-passes
    3   |   equivalent to existing "ghc -v"
    4   |   "ghc -v -ddump-most"
    5   |   "ghc -v -ddump-all"

4 & 5 are the same at the moment.  -dshow-passes also prints out the
passes in the driver, and some in the compilation manager.