eliminate meta_data parameter from chart generator functions
extract preparation code for splitted columns in a function
pass only relevant data to format_series
sort series descending
move format_series to chart/common.js and set it on App
use App.format_series in scenario1
make sorting optional
user App.format_series in scenario2
extract sort_serie
pass sort order as param to series formatter (-1/None/1)
sort descending in columns.js and splitted_columns.js
use App.format_series in scatter.js
use App.format_series in evolution_columns.js
Merge branch 'chart-series-formatter'