Add larger buffer for rendered pages (3-5 device screens)

[GoogleCodeExporter]

While reading, for examle, an illustrated article in DJVU (~10 pages per MB) on 
my tablet with 800x600 screen and 256M RAM, it looks like Vudroid renders and 
buffers approx. 1-1.5 screens of final picture, and when I try to read this 
portrait document in fit-width size on my landscape screen, then every time I 
need to look on, for example, the illustration on just a previous part of the 
same page (or, of course, on the previous/next page of doc) I have to wait 
while Vudroid re-renders that blanked squares of picture, "just forgotten" by 
him. It seems like Vudroid has fixed-size screen buffer that was made a long 
ago for low-RAM and low-res devices on those he was capable to store more than 
one screen in this. Now, the things are changed :) 

Is it possible to reconstruct something to feel free of lags when dragging 
across 2-3 nearest pages of current document? I think that with this amount of 
RAM it wouldn't be a great trouble. 

Thank You a lot!

Original issue reported on code.google.com by [email protected] on 12 Nov 2011 at 12:58