Removed one-off tools - tools that are used only once more than a year ago.

These are better done in SQL if needed, as SQL is more general and is easily accessible through sqlite and postgresql:

- `left_join`
- `sort`

These were quite application specific:

- `merge_fields`
- `max`

This would require a rewrite, as it was taking the width from the user instead of its input:

- `pad`
csv_add_id: modernized, installed as a script
removed script aliases
Updated README.md