Trim only one line at start and end

[dword-design]

Currently endent trims all start and end newlines. But it would be more flexible to only trim max 1 newline. This way we can create newlines in the template string. Problem is that the logic is in dedent and my PR is not getting merged. Also, I don't know what the state of the project is. Maybe some feedback here how to proceed. Here is the link to my PR in dedent:

dmnd/dedent#30