SeriesTitle

- Fix issue with it not being properly escaped
Support for dTable (Data Table) on multi-chart plots
Bugfixes

- @zoom_scale_normal, @zoom_scale_page_layout_view, @zoom_scale_sheet_layout_view all need to be set.  A default of 0 is incorrect according to the Open XML SDK 2.5 Validator.
- Due to the way serialized_attributes works, @name won't be set by default.  This should probably be fixed by having serialized_attributes use method-based accessors rather than instance vars.
Merge branch 'fixes'
Merge branch 'multi_chart'