Add extra template blocks to dashboard order templates

This also fixes some html errors (missing closing tag).
Show line ID on order detail dashboard page

This is needed as some error messages reference the line ID. They aren't
that helpful when you don't know which line is which.
Correct date field name in line detail template
Extend validation of line quantities submitted in order dashboard

Motivated by #988, this change adds extra validation for when quantities
are submitted on the dashboard page. Without this, negative and too-high
values can be submitted without getting blocked by validation checks.

Fixes #988