Open multiple documents together using Ctrl-O (Open File)

[hassankhaw]

Currently Markpad only allows a single document to be opened using the Menu->Open File, or Ctrl-O dialog box. Opening multiple documents requires you to repeat this process multiple times and each document is opened in a separate tab.
It would be great if the file selector allows selecting multiple files to open together.

[PathGao]

Tracked by #297 / #298. The Open File dialog now accepts multiple selections and opens them through the existing tab-management path. #298 is part of the current dependency chain.