Make first line of description the summary?

#### Feature request

When entering a multi line description, the output in all reports will always contain multiple lines, making it quite bulky. This is independent of the choice of a `description.count` or `description.oneline` column, because they only affect annotations, but not the description itself.

I suggest to use a column format similar to Git / Mercurial commit logs in the concise reports.

This column format will assume the description has the following format, similar to Git / Mercurial commit messages:
```
First line is summary

Additional details
```

In concise reports I would like only the first line / summary to be shown, while in the more detailed reports or the task details (`task ID`), I would show the whole blurbs.

People can be assumed to be familiar with this format and behaviour, as it is commonly used in e.g. Git or Mercurial, which I would assume most Taskwarrior users are familiar with.

Related: TW-1369 / #1397