Format final counts as a table

[mgrojo]

Currently, the summary counts are printed as a list:

------------------
- Failed     =  3
- Successful =  1
- Empty      =  0
- Not run    =  0

That turns into (note that the plain-text alignment is lost):

---

• Failed = 3
• Successful = 1
• Empty = 0
• Not run = 0

With a simple change of the output, it could be turned into a pretty table:

| Status     | Count |
|------------|-------|
| Failed     |  3
| Successful |  1
| Empty      |  0
| Not run    |  0

Status	Count
Failed	3
Successful	1
Empty	0
Not run	0

By the way, a Total count could also make sense.

N.B. I see that tables are not part of the CommonMark specification, so maybe you don't want to make it less interoperable. Feel free to close this, in such case.

[LionelDraghi]

Good Idea, and it is not more difficult to parse.

(I try to stick as much as possible to CommonMarks, but table is a must have, and I won't refrain because it's not in the base standard).

[mgrojo]

In fact, the table support is present in many Markdown implementations. Some time ago, I could check the basic format I used in this issue is supported by the three implementations that I was checking, namely GitHub, Pandoc and Jekyll.

[LionelDraghi]

This is the format I already use for the output of the grammar (list_grammarcommand), so it will be coherent.