Multi-line descriptions break the docblock format

[siggi-k]

Affects 2.0-beta5 (5b657bf).

A model with x-table: false renders every property description raw into the docblock, so a
multi-line description (YAML description: |) loses the * prefix from its second line on
and gains a stray empty line from the block scalar's trailing newline:

    /**
    * @var string Oldest day the requested series together can hold data for.
It is the earlier of the company creation date and the oldest counted booking.
Unlike dateFrom it does not follow the request, it describes the data itself.

    */
    public $windowStart;

Cause

src/generator/default/model.php concatenates the description without touching its newlines:

    * @var <?=$attribute->phpType.' '.$attribute->description.PHP_EOL?>

The class-level description in the same template already does it right:

 * <?= empty($model->description) ? '' : str_replace("\n", "\n * ", ' ' . trim($model->description)) ?>

So the attribute line needs the same trim() (kills the empty line) plus a str_replace() with
the 4-space prefix ("\n * ").

Scope

• Only model.php, i.e. x-table: false. dbmodel.php renders @var with the type alone, so
  DB-backed models are unaffected.
• Same file, minor: the class-level line prepends ' ' before the description ( * Aggregated …,
  two spaces) and always emits an empty * line before */.