Version 0.29

  Document usage of multiple platforms (issue #85):   https://github.com/xolox/vim-notes/commit/eaf2d44  Emit proper Markdown horizontal rulers in conversion to Markdown format:   https://github.com/xolox/vim-notes/commit/5ddf420  Merge pull request 98: Accept ``` code markers (similar to GFM*):   https://github.com/xolox/vim-notes/commit/6f4ad2b