More syntax to be user friendly

[fgallaire]

If it is a tips, it should be built-it:
http://txt2tags.org/tips.html#copyright-symbol

And we could talk about this again:
#176

[fgallaire]

We have pre-formatted line and area:
http://txt2tags.org/userguide/VerbatimLineVerbatimArea.html

But we don't have formatting line and area. For example right align could be done with the obvious:

>>> line at right
and
>>>
area at right
>>>

but the obvious center align:

=== centered line
and
===
centered area
===

could be a little confusing with the title syntax.

The Trac solution to add "processors" to the area could be elegant:
http://trac.edgewall.org/wiki/WikiProcessors

With a lighter syntax Github Flavored Mardown adds a programming language name to ``` for syntax highlighting:
https://help.github.com/articles/github-flavored-markdown/

We could keep the default to pre-formatted for the ``` syntax, but add optional options to change this behaviour.

```> line at right
```= centered line

[fgallaire]

A need for some users, this one uses a no border table to center text in HTML:
https://mostlylinux.wordpress.com/textanddocument/txt2tagscheatsheet/#centeredlineoftext

[fgallaire]

#201

[fgallaire]

#112