[Tilesathome] simple optimization instead of asynchronous upload

[Łukasz Stelmach]

Hello.

I've set up T at H yesterday and noticed a small efficiency problem with a
forked setup. tilesGen.pl starts with a single, simple z12 256x256 tile
and goes towards more complex pictures. This leaves it with a *single* z17
inkscape trying hard. It would be much more efficient if z17 was the
first zoom levevel to deal with because (lets assume a spherical cow)

Let Fork equal 2.
Let time(z_n)=4*time(z_{n-1})
If time(z_12) = 1 then time(z_12..z16) = 341 and time(z17) = 1024

If the first thread starts with z17 then the other can do all other
levels in parallel

If time(z_n) = 2*time(z_{n-1})
   then 
time(z_12..z16) = time(z17)-time(z_12)

-- 
Łukasz Stelmach