Adding panels for clickable icons for quicker access to all "Effects" from the workspace

[CC-Hsu]

Description Hi, Team,

There are many special effects available in Pinta 2.1.1 now, but users need to choose from the Menu Bar, which is not convenient enough.

It would be great if Pinta can provide a new right-hand side window for "Effects" for quickly accessing all the effects to use.

Best Regards.

[cameronwhite]

This probably first requires updating all the effects' icons to modern SVG symbolic icons, since most of them haven't been updated yet. I don't object to having an optional pane that isn't shown by default, but it probably requires some thought of how the icons would be organized since there are a lot of effects