When vw exitcode != 0, output the stderr file to the user since the
actual reason for the failure is likely in there.
Errors should go to stderr
Merge branch 'runtest'

Conflicts:
	test/RunTests
Merge branch 'master' of git://github.com/JohnLangford/vowpal_wabbit
Merge branch 'master' of git://github.com/JohnLangford/vowpal_wabbit
Merge branch 'master' of git://github.com/JohnLangford/vowpal_wabbit
Merge branch 'master' of git://github.com/JohnLangford/vowpal_wabbit

merge with jl master
vw-top-errors: better comments + add copyright/licence notes (same as vw)
Avoid uninitialized warnings on too few features or deviant examples
Switch to mean-of-weights by default.  Add -s option for sum-of-weights
Merge pull request #321 from arielf/vw-top-errors

vw-top-errors small bug fixes + allow sorting by sum as well as mean of weights