linechart: show all commodities, filter empty series
linechart: show all commodities, filter empty series

fix #281
close #287

corani/beancount-web,beancount/fava,yagebu/fava,corani/beancount-web,corani/beancount-web,aumayr/beancount-web,aumayr/beancount-web,corani/beancount-web,yagebu/fava,beancount/fava,aumayr/beancount-web,beancount/fava,beancount/fava,aumayr/beancount-web,yagebu/fava,beancount/fava,yagebu/fava,yagebu/fava