2191: focus on CssBox.ParseWordContent
2194: developing ...
2196:
2197: ContentRuns

manage text buffer of CssBox and
HtmlElement with ContentRuns
2198: ContentRuns fixes
2199:refactor
2200:fix
2203: RunCollection
2203.1 err
2205: RunCollection

Bug fixes
Merge branch '2203.1' into v1.7dev
Merge branch 'v1.7dev' into v1.7