Undo/redo issues #64
Description
When performing a redo of an undone paste in the canvas, the paste command is repeated, but any changes made in the clipboard and/or the paste mode are not taken into account, resulting in whatever is currently in the active clipboard/slot being pasted with the active paste mode, which will not necessarily be the original canvas contents that were removed by the undo operation. Additionally, even when paste mode is set to all, paste-char-n commands use default color if no color value is set for a given object, and this also applies to redone paste-char-n operations, which may have originally been performed with no default color set but redone with a specific default color active.
Also, pastes made while in color paste mode cannot be undone (and I seem to remember this being mentioned in the tutorial or some other documentation, suggesting that this was a choice), but seemingly every other method of assigning a new color value to an existing object can be undone.