Patch for some minor changes arising during an FS development about fusepy HOT 2 OPEN

Thanks for the feedback and sorry for the huge delay. My comments concerning 
your patch:
1) I try to keep the structures as small as possible for portability reasons. 
Is there a specific field that you want access to?
2) In which cases would you need to instantiate FUSE with help=True?
3) It is not just for portability, but also for more flexibility in the 
implementation of the filesystems. I see your rationale but I'll leave it as 
is, as this change could break existing filesystems too.
4) I was concerned about using OSError too, I agree that using an OSError 
subclass is better, committed.
5) I think EROFS is a better default, as it could be left as is for small toy 
filesystems (like context.py). For anything more sophisticated it is going to 
be overriden anyway.
6) Committed.

1) Yes, I need to return f_namemax
2) The canonical usage of FUSE flags is to add your own options, and then parse 
them all, and request FUSE to dump it's FUSE specific options. It's been a 
while, and I've since ported to C, but this is how it's done: 
http://code.google.com/p/cpfs/source/browse/mount.cpfs.c#24 Also note that wrt 
to the original usage of help in the patch, it's very difficult to find a 
complete listing of the available FUSE options, passing -h is the only way. 
Perhaps instead you could provide a function doing the FUSE opt dump as I've 
done from C.
3) Yes I can understand this. This is me trying to push type safety onto 
Python. Bad practice but a few bugs were masked by me passing the wrong fields 
back.
4) It's awful and a PITA that the strerror field is not generated by default in 
OSError anyway. From the changes in r57 (I can't comment on that you might have 
disabled it or something), I don't think you need to change the docstring to 
say "throw a FuseOSError", as OSError is still handled. FuseOSError here just 
generates cleaner errors for the default handlers.
5) Maybe you could consider ENOSYS as well. This might impact portability, I'm 
not really fussed about this.
6) Awesome, thanks.