markdown/pagemodel: Add support to detect links

[oliviermartin]

This change detects URL that are not captured by Markdown
syntax.
The code adds '<' and '>' to these links.

This change should fix #41.

[paulvi]

Note: great, however is this automatic change?

I can lead to problem that .md files will become as change in version control system,
while user had no intention to change

Should it be optional ?

[oliviermartin]

That's a good question. But the '<' & '>' are only added into the intermediate representation given to the Markdown library. Like that the Markdown library interprets the link as a Markdown link.

So, they do not appear into the source document (ie: the source document is kept unchanged).

[winterstein]

the source document is kept unchanged

That's good. Thanks Olivier.
This sounds like a good improvement, so I'm going to go ahead and merge. NB: I haven't tested it out.

[paulvi]

NB: I haven't tested it out.

me too, so asking.

So if it for preview it will not fix #41 "Link highlight is misleading"

I thought, could there be option to insert '<' & '>' on save...

[paulvi]

ref #52