[BUG #7142] dangling comments now stay with their preceding code

- also add support for prettypCommentsTrailingCommentCols,
  prettypCommentsTrailingKeepColumn, prettypCommentsInlinePadding

- open issue: if a multi-line block comment dangles with its first line
  and continues on the next, what should be the indentation of the next?
- open issue: the config settings pretty-print/comments/trailing are now applied
  to trailing (dangling) block comments as well as line-end comments; which i
  think makes sense; but then the docs (config ref) needs to be adapted