Nested list adds extra space in Markdown Formatting

#### Steps to reproduce
1. Begin writing a list in Markdown using '-' or '*'
2. Make a tab indent of a list item using the same symbols
3. Hit return and make an un-indented list item. using the same symbols.
4. Preview

#### What I expected
Formatting like this:
- Item 1
- Item 2
- Item 3
With no space between items 2/3

#### What happened instead
-Item 1
- Item 2

- Item 3

As you can see a space is inserted between items 2 and 3 automatically. I would rather have the space be something I have control over.

#### Simplenote version
- iOS app and MacOS app.
- Does not happen in the Web App for me

#### iOS version
4.6.5

#### Screenshot / Video


)

Reproduce the nested Markdown-list example in the iOS and macOS apps, then compare it with the Web App where the issue does not occur. The work is done when returning from an indented item does not insert an unwanted blank space, while deliberate spacing remains possible.

Written by the indexing model from the issue text.