browse: When sorting by size, offset directories
browse: When sorting by size, offset directories

Assigns negative sizes to directories in order to have them listed reliably
before any zero-sized files. That order is what most users expect when
sorting by size.

As side effect directories will appear before files on all filesystem
implementations. To give an example: before this change directories had a size
of 4 KiB when using Linux with ext4 or tmpfs, and with ZFS a size resembling
an estimation of the number of leaves within said directory.

cez81/caddy,dusty/caddy,tw4452852/caddy,tobya/caddy,tobya/caddy,cez81/caddy,evermax/caddy,devangels/caddy,ollie314/caddy,ollie314/caddy,ollie314/caddy,captncraig/caddy,evermax/caddy,dusty/caddy,captncraig/caddy,pyed/caddy,dusty/caddy,captncraig/caddy,elcore/caddy,ollie314/caddy,tw4452852/caddy,pedronasser/caddy,cez81/caddy,tobya/caddy,pyed/caddy,yukimochi/caddy,DenBeke/caddy,evermax/caddy,tobya/caddy,pedronasser/caddy,joshix/caddy,elcore/caddy,devangels/caddy,DenBeke/caddy,tw4452852/caddy,pedronasser/caddy,devangels/caddy,elcore/caddy,DenBeke/caddy,joshix/caddy,joshix/caddy,dusty/caddy,yukimochi/caddy,DenBeke/caddy,pedronasser/caddy,pyed/caddy,yukimochi/caddy,tw4452852/caddy,pyed/caddy,evermax/caddy