Automatically wrap lines in less than the window width

Currently Mnemosyne only wraps lines when they are longer than the full width of the window. This means a line has to be very long indeed, even in the small default windows; if you use a tiling window manager, or use Mnemosyne full-screened (as I do), the line has to be excruciatingly long before it will wrap. Much better would be at least an option to have it wrap at a comfortable number of characters, if the window is not narrower. I suggest around 70-80 characters/columns would be a good default. (I currently insert linebreaks manually to make things usable, but I'd rather not as the insertions are fairly arbitrary and are not semantically meaningful and do not adjust with window size.)