Added chart object positioning and sizing.

Allow positioning of plotarea, legend, title and axis names.
Issue #66.
Minor doc update.
Added set_title() option to turn off automatic title.
Minor update to set_legend() API.
Improved defined name validation.
Fix for modification of user params in condtional_format().
Prep for relase 0.4.9
Added Chartsheets: worksheets with single charts.

Issue #10
Added Python 2/3 Unicode examples.
Added series name list data to examples.
Minor refactoring of add_Xsheet() methods.
Updated Python 2/3 Unicode examples.
Prep for relase 0.5.0
Fix for axis name font rotation.
Removed Python version 2.5.
Added test for chart title rotation.
Fix for Pie chart legend fonts.
Added test for delete_series in Pie charts.
Added test for Pie chart legend overlay.
Added interval unit for category axes.

Issue #69.