Add a description column to be used as test name or comment to describe what each test does

Currently, AcceptanceMark does not provide a way of describing what each test does.
It would be useful to add a `description` column to describe what the test will do. Example:

| year:Int | month:Int | day:Int | language | dateStyle | | localizedDate | | description |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 2016 | 9 | 16 | en | short | | 9/16/16, 5:30 PM | | formats the date in English |
| 2016 | 9 | 16 | fr | short | | 16/09/2016 17:30 | | formats the date in French |
| 2016 | 9 | 16 | it | short | | 16/09/16, 17:30 | | formats the date in Italian |

One way to do this is to add an additional _optional_ column separator after the outputs. The additional description column could be used to name the test so that the generated method could change from this:

```
func testDateFormatting_row1()
```

to this:

```
func testDateFormatting_row1_formatsTheDateInEnglish()
```

No files or tests are named. Start by locating the Markdown table parser and the generated test-method naming logic, then trace how optional columns and output separators are handled. Done means an optional description column can describe each test and can produce a readable generated method name without breaking existing tables.

Written by the indexing model from the issue text.