compute cumulative y-values
enable stacked bar chart :moneybag:
call a range a range and make domain run from zero for bars
doc and restuc
testje
more tests
zap console info
Sjangtjes
Update CHANGES.rst
jshint
changes.rst
Merge pull request #248 from nens/Ernst_stacked_bar_char

DONE: Ernst stacked bar char
merge conflict