Secondary axis support
Merge branch 'master' of https://github.com/wiktorn/pygal into 2ndary_axis
Added secondary axis support to Line
Extend tooltips with x value.
remove debug print
Fix margin settings
Remove surplus CSS declarations for secondary axis
Remove surplus ","
Remove secondary_box - not used in code
Remove duplicated _secondary_min method
Fixed CSS declarations - this are needed for proper alignment of values on secondary y axis
Removal of force_order - not needed in final solution
fixing whitespaces and box computations
Whitespace cleanup and comments cleanup
Fixed setting of marigins - now on the left side are primary
 labels, and on right side - secondary labels - that needs to
be taken into consideration, when computing margins.
Merge remote-tracking branch 'wiktorn/2ndary_axis'
Adapt #20, fix tests (x_labels at None), fix pep8. Make it work with stacked lines
Fix horizontal and fix margin for 2ndary labels
Fix the rest as much as I can with secondary