Re: Improve markup->string (issue 347000043 by address@hidden)

[dak]

I wonder whether it might be reasonable to just have all markup commands
with a last argument of markup? produce their last (recursively treated)
argument as default, and possibly all markup list commands with a last
argument of markup-list? similarly produce their last argument?  That
leaves fewer commands to cater for and would also make some user-defined
commands work reasonably well.

https://codereview.appspot.com/347000043/