fix whitespace encoding in urls

[dirkjf]

Keep encoded links encoded. With this PR markdown like this:

![internal](image%20wtih%20spaces.jpeg)
![exernal](https://examle.com/image%20wtih%20spaces.jpeg)

Will result in:

<img src="image%20wtih%20spaces.jpeg" alt="internal">
<img src="https://examle.com/image%20wtih%20spaces.jpeg" alt="exernal">

Instead of not:

<img src="image wtih spaces.jpeg" alt="internal">
<img src="https://examle.com/image wtih spaces.jpeg" alt="exernal">

See also issue #1622

[rhukster]

Without even running any tests, I know this will be an issue because you've removed an important bit of logic.

[dirkjf]

Without even running any tests, I know this will be an issue because you've removed an important bit of logic.

This is restored and currently this PR will only encode whitespaces in a URL.