Send log messages to stderr. (Issues #604, #446)
Send log messages to stderr. (Issues #604, #446)

This is probably controversial. My motivation is that output from
commands like `stack path --local-install-root` should be consumable
by scripts, and so shouldn't be cluttered with unpredictable log
messages. There is probably some good reason that non-error/warning
log output was still going to stdout in
4460c36814e8312afd8429461497faafe5955175, but it's not explained in

martin-kolinek/stack,Fuuzetsu/stack,rrnewton/stack,mathhun/stack,athanclark/stack,keent/stack,wolftune/stack,rvion/stack,kairuku/stack,ant1441/stack,lukexi/stack,juhp/stack,fizruk/stack,rekka/stack,bollu/stack,adinapoli/stack,vigoo/stack,juhp/stack,akhileshs/stack,Denommus/stack,luigy/stack,sjakobi/stack,phadej/stack,akhileshs/stack,AndrewRademacher/stack,AndrewRademacher/stack,vigoo/stack,bixuanzju/stack,chadbrewbaker/stack,ant1441/stack,markus1189/stack,mathhun/stack,chadbrewbaker/stack,AndreasPK/stack,MaxGabriel/stack,Blaisorblade/stack,tedkornish/stack,agrafix/stack,athanclark/stack,rrnewton/stack,AndreasPK/stack,joozek78/stack,DanielG/stack,markus1189/stack,kairuku/stack,fizruk/stack,adinapoli/stack,wskplho/stack,meiersi-11ce/stack,chreekat/stack,supermario/stack,achernyak/stack,bixuanzju/stack,soenkehahn/stack,meiersi-11ce/stack,soenkehahn/stack,harendra-kumar/stack,chreekat/stack,wskplho/stack,keent/stack,anton-dessiatov/stack,Heather/stack,harendra-kumar/stack,mrkkrp/stack,supermario/stack,Blaisorblade/stack,Heather/stack,GaloisInc/stack,Denommus/stack,cabrera/stack,martin-kolinek/stack,sinelaw/stack,agrafix/stack,MichielDerhaeg/stack,cabrera/stack,robstewart57/stack,Fuuzetsu/stack,duplode/stack,sjakobi/stack,phadej/stack,narrative/stack,rvion/stack,sinelaw/stack,MaxGabriel/stack,lukexi/stack,anton-dessiatov/stack,rekka/stack,luigy/stack,narrative/stack,mrkkrp/stack,deech/stack,duplode/stack,joozek78/stack,DanielG/stack,wolftune/stack,rubik/stack,rubik/stack,achernyak/stack,MichielDerhaeg/stack,tedkornish/stack,Andrew-the-Ubergeek/stack,deech/stack,bollu/stack,robstewart57/stack,Andrew-the-Ubergeek/stack,GaloisInc/stack