Add support for associated character properties when importing from RTF. Such properties are 
\rtlch, \ltrch, and the associated control words like \afN, \loch, \hich, and \dbch.
Currently, runs/bullets with such properties set could be imported with different character properties.

Workaround: Use the supported \f tag for the most common low-ANSI characters, for example by:
- doing the following replaces in the source document:
\loch\af -> \loch\f
\dbch\f -> \dbch\af
- (Possible workaround) Re-saving the document with MS Word