Support for "notebook.textbundle" filesystem architecture format

[MrPike]

General information

App version: v2.2.5 (107)
System: Android 9

Feature request

First, thank you to all contributors for developing this fantastic application.

I would like to propose the introduction of native TextBundle support within Markor. TextBundle is a relatively simple and open specification that has good adoption amongst other note-taking apps. Support for TextBundle support will facilitate interoperability between Markor and other note apps.

[gsantner]

Till date I haven't used or discovered a single desktop or mobile application that makes use of this format. Even more, what I see there are many proprietary applications like Bear.

I want Markor to keep file-centric and let users decide whereever they want to save their stuff. Introducing a not really wide adopted metadata+file structure doesn't seem like a good addition to me.

Previously thought this is more about a format in terms of the textfile, but this is about filesystem architecture.