Fix for list item spacing with dynamic type fonts

This release makes sure the space between list-items is correctly rendered with large fonts

Dynamic type and short url's

This release adds support for Dynamic Type in Swift. As you can see in the read me, it will be as simple as opt-ing in to font scaling by doing the following:

    markDownView.hasScalableFonts = true

It also allows setting a maximum font-size related to the font-scaling, such as:

        markDownView.styling.paragraphStyling.maximumPointSize = 24

• Add support for https://m2mobi.com style links

Fixes bug with multiple link's that contain a title on the same line, such as

• Fixes bug with multiple link's that contain a title on the same line, such as

"[Google](https://www.google.com/ "great-url-title") test [Google](https://www.google.com/ "a11y title") and even more [[https://www.apple.com](https://www.apple.com](https://www.apple.com]%28https//www.apple.com) "Apple-aria-label") test"

• Removes hardcoded Swift 4 version

Fix links that contain special characters in the aria-label

Fix links that contain special characters in the aria-label

Fix links such as Alt text, which has a special character in the aria-label "Some-test"

Bugfix UrlOpener

1. Since the last release, urlOpener was no longer working. This release fixes the issue.
2. This issue improves the ListRule, allowing anywhere between 1 and 4 spaces after the * symbol

Support for title in link tags

Adds support for links like: [Google](http://www.google.com "custom title").

Also fixes a bug where detected rules inside a link would not be discarded correctly.
[Google](http://www.google.com/path_nested_italic_item_s) would appeared incorrectly.

Custom LayoutBlockBuilders on MarkdownTextView

Added feature on MarkdownTextView to add custom LayoutBlockBuilders.

i.e.

markdownTextView.addViewLayoutBlockBuilder(MyCustomLayoutBlockBuilder())

markdownTextView.addAttributedStringLayoutBlockBuilder(MyCustomLayoutBlockBuilder())

Swift Package Manager support

Resolves

• #97

Breaking changes

• In order for URL handling to keep working (in some cases), func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool has to be implemented in AppDelegate

Notes

• Since this release is only beneficial for SPM users, there's currently no CocoaPods version of this code (yet).

MarkDownTextView expose UITextView creation

Resolves #92

Allow subclassing MarkDownTextView

Changed access of MarkdownTextView from public to open to allow subclassing