Formattable elements

[englertjoseph]

Textruns and Paragraphs can be created with formatting from a bookmark by supplying a hash to the bookmark methods:

1. insert_text_before(text, formatting={})
2. insert_text_after(text, formatting={})
3. insert_multiple_lines(text_array, formatting={})

Or applied to an already existing Run or Paragraph using
element.apply_formatting(formatting)
Textruns can also be formatted whilst changing the text with:
textrun.set_text(content, formatting={})

Allowed formatting for:

Text runs

• :italic => boolean
• :bold => boolean
• :underline => boolean
• :font => 'font_name'
• :font_size => font_size
• :color => color as hex string e.g. 'FF0000' for red

Paragraphs

• :alignment => 'center', 'left', 'right'

fixes #16