Sublime 3 plugin (tested with Build 3126)
This plugin reorders flow text within comments.
The default keycode is shift+alt+f shift+alt+f.
It does not work with different types of comments at the same time. So selecting all comments in the example (/// and //) would produce rubbish.
Currently works with #, //, ///, -- and //!. Multi line comments like /* */ are not supported.
This plugin is rough, but does it's job well enough. If it doesn't work out, a undo (ctrl+z) will revert the changes.
The line length is specified by the last array element of the rulers setting in the default sublime setting file or defaults to 80.