GeoDa 1.8.6 (with Test Mode)

bug fixes

#422 GeoDa memorizes last input in DB input not working; Invalid connection causes crash;
#421 space-time regression: strange error in loading space-time weights gal file
#420 1.8.6 GeoDa with TestMode
#419 averages chart: correct d.f. for difference in means test? #419
#418 auto update needs "testing version" and handle poor internet connection