Iroin-python-pptx

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- Add `SlideShapes.build_freeform()`, allowing freeform shapes (such as maps)
to be specified and added to a slide.
- Add support for patterned fills.
- Add `LineFormat.dash_style` to allow interrogation and setting of dashed
line styles.

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- Add `SlideShapes.add_movie()`, allowing video media to be added to a slide.

- fix 190 Accommodate non-conforming part names having '00' index segment.
- fix 273 Accommodate non-conforming part names having no index segment.
- fix 277 ASCII/Unicode error on non-ASCII multi-level category names
- fix 279 BaseShape.id warning appearing on placeholder access.

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- 267 compensate for non-conforming PowerPoint behavior on c:overlay element

- compensate for non-conforming (to spec) PowerPoint behavior related to
c:dLbl/c:tx that results in "can't save" error when explicit data labels
are added to bubbles on a bubble chart.

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- add Chart.chart_title and ChartTitle object
- 263 Use Number type to test for numeric category

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- add DataLabel.font
- add Axis.axis_title

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- add support for NotesSlide (slide notes, aka. notes page)
- add support for arbitrary series ordering in XML
- add Plot.categories providing access to hierarchical categories in an
existing chart.
- add support for date axes on category charts, including writing a dateAx
element for the category axis when ChartData categories are date or
datetime.

**BACKWARD INCOMPATIBILITIES:**

Some changes were made to the boilerplate XML used to create new charts. This
was done to more closely adhere to the settings PowerPoint uses when creating
a chart using the UI. This may result in some appearance changes in charts
after upgrading. In particular:

* Chart.has_legend now defaults to True for Line charts.
* Plot.vary_by_categories now defaults to False for Line charts.