Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
Factor out inode resizing into a separate Ext2FSInode::resize() function.
This is then called both from write_bytes() and truncate().
This patch finally implements freeing of blocks when an inode shrinks.
