[Feature request] - Add optional context menu for supported filetypes

[p-yukusai]

Long time user of PhotoDemon, it's my go to for quick image editing, and to that end I would love to see an option to add the current PhotoDemon executable to the context menu for all supported filetypes to make it as easy as a right-click to immediately edit images, I've already done this manually and it is incredibly helpful whenever I need said fast editing.

This is easily done by just adding registry keys to "Software\Classes*filetype*\shell", would be pretty neat as well if it had PhotoDemon's logo on it by adding a "Icon" REG_SZ that points to the current PhotoDemon directory and getting the icon from there, one problem this would have is the portable nature of the app, since moving the application would break this, getting the regkey and changing it should it be necessary if the context menu is enabled would be something to consider.

Much love!