Markdown: 2 spaces or more at line end should force line break inside paragraph

[matwachich]

Checklist

• [X] I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• [X] This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

According to markdown spec: When you do want to insert a <br /> break tag using Markdown, you end a line with two or more spaces, then type return.

How to reproduce

Run the example

Screenshots

No response

Example code

package main

import (
    "fyne.io/fyne/v2"
    "fyne.io/fyne/v2/app"
    "fyne.io/fyne/v2/container"
    "fyne.io/fyne/v2/widget"
)

func main() {
    a := app.New()
    w := a.NewWindow("Test")

    rt := widget.NewRichText()
    rt.Wrapping = fyne.TextWrapWord
    in := widget.NewMultiLineEntry()
    in.Wrapping = fyne.TextWrapWord
    in.TextStyle = fyne.TextStyle{
        Monospace: true,
    }
    in.OnChanged = func(s string) {
        rt.ParseMarkdown(in.Text)
    }

    in.SetText(`We want to make a line break just here  
after the first line.

This is another paragraph`)

    w.SetContent(
        container.NewGridWithColumns(2, in, rt),
    )
    w.Resize(fyne.NewSize(800, 300))
    w.ShowAndRun()
}

Fyne version

2.3.2

Go compiler version

1.20

Operating system and version

Windows 10

Additional Information

No response

[vinser]

Hi I have to add a little This code will show flaws in Markdown implementation

package main

import (
    "fyne.io/fyne/v2/app"
    "fyne.io/fyne/v2/widget"
)

func main() {
    a := app.New()
    w := a.NewWindow("Fyne Markdown")

    richText := widget.NewRichTextFromMarkdown(`
![image](appIcon.png)
## Look at Fyne Markdown implementation ##
---
Heading
=======

Sub-heading
-----------

# Alternative heading

## Alternative sub-heading

Paragraphs are separated 
by a blank line.

Two spaces at the end of a line *here* 
produce a line break.

---
*Created using [Fyne](https://fyne.io) GUI library*

*App icon design by [Icon8](https://icon8.com)*`)

    w.SetContent(richText)
    w.ShowAndRun()
}

run it and you'll get

1. Image must be left aligned
2. Two spaces must do line brake
3. Links surrounded by italicized text must be italicized too

[vinser]

My feature request #3810 is the same theme

[vinser]

The above Markdown should look like this

Look at Fyne Markdown implementation

---

Heading

Sub-heading

Alternative heading

Alternative sub-heading

Paragraphs are separated by a blank line.

Two spaces at the end of a line here produce a line break.

---

Created using Fyne GUI library

App icon design by Icon8