Hide markdown view on plugin load

[dreamflasher]

Currently the split position is not saved per note, so one needs to resize every time when opening. There is no need for the code view with this plugin, so I suggest hiding it on plugin load.

[ThibaultJanBeyer]

That is indeed a good idea, if you can, feel free to add that, that would be an awesome contribution :)

[chr15m]

@ThibaultJanBeyer what about inserting the plugin UI into the rendered view instead? Then people can use the existing interface to switch between data and view.

[laurent22]

Using this plugin to save the split state could be a workaround: https://github.com/benji300/joplin-persistent-layout