Compute Envelope and Average of Simulations of K-fns
Computes envelope (upper and lower limits) and average of simulations of K-fns

Syntax
	Kenvl(fs, nsim, ...)
Input
fs    full scale for K-fn
nsim  number of simulations
...   arguments to produce one simulation

Oupput
list with components:
x       distances
lower   min of K-fns
upper   max of K-fns
aver    average of K-fns

See Also
`Kfn', `Kaver'

Examples
towns <- ppinit("towns.dat")
par(pty="s")
plot(Kfn(towns, 40), type="b")
plot(Kfn(towns, 10), type="b", xlab="distance", ylab="L(t)")
for(i in 1:10) lines(Kfn(Psim(69), 10))
lims <- Kenvl(10,100,Psim(69))
lines(lims$x,lims$l, lty=2)
lines(lims$x,lims$u, lty=2)
lines(Kaver(10,25,Strauss(69,0.5,3.5)))