Make markdown links consistent on cursor exits

Make the versions of link with and without * behave alike:

-   don't set the 0 location so that the cursor exits.
    Having a 0 in the title is bad because titles are short.

-   either open a new line at end for both, or for neither

    The only case where the newline is certain is for link definitions.
> Checking if I understand: [${1}](${2}) is exactly the same as [${1}](${2})${0}, so adding a ${0} to the end wouldn't change anything is that so? And the advantage of [${1}](${0}) is that it has one less stop.

yes. 

> Performance is usually not an issue unless people paste code. For one sentence or even one paragraph tabstops you can use whatever pleases you. But this is bad:

~~~
if ($1) {
   $2  // <- this should be $0
}
~~~~

People occasionally do this for the convenience of jumping back to $1 tabstop, but the middle tabstop should be $0 since regular coding will then continue and UltiSnips should not diff everything anymore.