Percent encode parenthesis in URL when creating Markdown link

[leesei]

URL: https://www.wikiwand.com/en/Ring_(mathematics) "Tab link -> Markdown": [Ring (mathematics) - Wikiwand](https://www.wikiwand.com/en/Ring_(mathematics)) which caused problem in some Markdown parser

I recommends outputting this: [Field (mathematics) - Wikiwand](https://www.wikiwand.com/en/Field_%28mathematics%29)

[leesei]

Also encode space as %20

[BlackGlory]

This issue is more complicated than I thought. I found that brackets are explicitly listed as reserved characters in the URL encoding. A Markdown parser should have the ability to distinguish between URLs and Markdown syntax, and if it can't, then it needs to be fixed. This extension should not change the output for this particular case.