Canvas support

[dxcore35]

Allow the Canvas file to be the folder note! Use same logic as for .md file but allow .canvas extension.

[batrand]

Would like to voice my support for this feature as well. I have several 'moodboard' canvases, and each has an _attachments folder containing the media. If the canvas file can be the folder note, then I can stick the _attachments inside the folder, decluttering the explorer view.