VStream raster, first cut

[Tuomas Lukka <lukka@xxxxxxxxxxx>]

Ok, I just committed the first "odd" raster that's still somewhat
integrated (unlike the TextCloud). It's the VStream raster which simply
draws the text in the cells on the rank on d.2 from the cursor, breaks
lines suitably and billows it (the part near the cursor is drawn in a
bigger font).

The code is slightly more complicated than I'd like - I'll have to find
ways to whittle it down a little later.

Adding this new visual mode does increase the power quite nicely even
though it is at such a rudimentary stage. 

Please, take a look at it and think about what would be the nicest
extension to have next; animation is coming soon but as for other stuff, I
don't know what to prioritize yet.

	Tuomas