Start userspace shell on boot
sh: don't print arguments; fix typo
Improve ls on symlinks
sh: read /etc/shrc, support # comments, fix buffer size bug
ls: support @ sigil for symlinks (ls -F)
Update TODO, simics.sh, stat.h, fix initrd comments. No major changes.
initrd: fix st->st_size. Solves scandir() page fault.

Previously, st_size for directories was simply set to the number of children.
Instead, it's now set to the approximate (it overestimates a bit by design)
number of bytes required to store struct dirents for all those children.
Add boot_finished(), to aid in setting simics bookmarks post-boot
Update README