[+] CHART :: Add background features
[*] CHART :: Use CSS rules
[+] PLOT :: Add ClusteredColumn plotter
[+] PLOT :: Add StackedColumn plotter
[+] CHART :: Several group per chart
[*] CHART :: Fix style and demo
[*] PLOT :: Fix ClusteredArea
[+] CHART :: Get header info, name and type
[+] CSV :: Add an expression parser
LEXER :: [/] Split Lexer and Expression resolver
[\] Merge with spreadsheet branch
[*] CHART :: Fix horizontal background