fix build of puffs examples; need _KERNTYPES for register_t

I wasn't going to add any more silly examples, but I'll bite for
this one, since it's a good exercise ..

Add icfs, which does the same thing as the refuse-based icfs agc
added earlier this week, i.e. null-mounts & converts the entire
namespace to lowercase. However, it's a fun comparison, since this
is implemented in a completely different fashion from the refuse
version.

s/demostrates/demonstrates/ in comment.

branches: 1.11.72;
fix more A0

Add -p for presenting the directory listing in the original case.

branches: 1.9.6; 1.9.10;
Rototill.

Ok, ok, a few more words about it: stop holding puffs_cc as a holy
value and passing it around to almost every possible place (popquiz:
which kernel variable does this remind you of?). Instead, pass
the natural choice, puffs_usermount, and fetch puffs_cc via
puffs_cc_getcc() only in routines which actually need it. This
not only simplifies code, but (thanks to the introduction of
puffs_cc_getcc()) enables constructs which weren't previously sanely
possible, say layering as a curious example.

There's still a little to do on this front, but this was the major
fs interface blast.

use puffs_daemon() instead of daemon()

Actually, daemonize the file servers before mounting. I might require
at some point that the local protocol handler does not change after
the file system has been mounted.

Pull the daemonizing code out of the library mainloop into the file
servers. Calling daemon() (i.e. fork()ing) inside a library can
cause nice surprises for e.g. threaded programs. As discussed with
Greg Oster & others.

branches: 1.5.4;
* add mntfromname parameter to puffs_init()
* set it in file servers

PUFFS_KFLAG_NOCACHE became two, so introduce the command line options
-o nonamecache and -o nopagecache and adapt file systems where necessary.

cast tolower() arg to unsigned char

use puffs_null_setops()

I wasn't going to add any more silly examples, but I'll bite for
this one, since it's a good exercise ..

Add icfs, which does the same thing as the refuse-based icfs agc
added earlier this week, i.e. null-mounts & converts the entire
namespace to lowercase. However, it's a fun comparison, since this
is implemented in a completely different fashion from the refuse
version.