This will add slide layouts names as attributes to `SlideLayouts` instance.
All layouts names will be converted to CamelCase without spaces.
If the converted name is a valid identifier and is not used already by `slide_layouts` instance it will be assigned as an attribute to `slide_layouts`.
Also all available layouts will be available (as seen in PowerPoint) as a list accessible with attribute `slide_layouts.available_layouts`
After that - using available layouts is as easy as accessing any other attribute.

For example with the standard template available with `pptx`:

    pres = Presentation()
    print(pres.slide_layouts.available_layouts)

Will produce:

    ['Title Slide', 'Title and Content', 'Section Header', 'Two Content', 'Comparison', 'Title Only', 'Blank', 'Content with Caption', 'Picture with Caption', 'Title and Vertical Text', 'Vertical Title and Text']

And using `Title Slide` is then as easy as:

    pres.slide_layouts.TitleSlide