add options for link inline

[danielklecha]

Hi,

I want to fix issue #886.

I added options class but it's only used if user replace default parser.
Feel free to comment and give me clues :)

AutoLinkOptions has few more properties but I didn't implement it.

Does anything else should be changed?

[danielklecha]

@MihaZupan could you recheck my changes?

1. I added comment with license information
2. I created LinkOptions.cs and associated it with all four parsers
3. I moved EnableHtmlParsing into options class in AutolinkInlineParser - we break backward compatibility in this place but I think that we should keep options in one place.
4. I think that I added _target attribute correctly but please check it because I could have missed something.

[danielklecha]

I fixed tests.