faster stack raster files

fun_fasterstack.R

## Thanks RobertH for sharing this very useful function
## http://stackoverflow.com/a/9937083

fun.quickstack <- function(f) {
  r <- raster(f[1])
  ln <- extension(basename(f), '')
  s <- stack(r)
  s@layers <- sapply(1:length(f), function(x){ r@file@name = f[x]; 
  r@layernames=ln[x]; r@data@haveminmax=FALSE ; r })
  s@layernames <- ln
  s
}