Give user the option to set a format that applies to the entire RichTextView

[AdamMc331]

Consider adding an option to format the entire RichTextView. Currently the user could do formatSpan(0, string.length()....) but it would be nice to have a convenience method that formats the whole string, and stays even after setText() is called again.

[rhari991]

Also we can allow the user to format the whole string through XML attributes.