Implement additional FUSE operations.

Implement additional FUSE operations.

Implement all of the following:
 - opendir
 - releasedir
 - fsyncdir
 - init
 - destroy
 - access
 - create
 - ftruncate
 - fgetattr
 - lock
 - utimens
 - bmap

Also replace the deficient readdir() operation with my own, which
allows for significantly greater efficiency, and supports directory
handles (as can be returned from opendir()). Also also, instead of
using static initialization of fields to zero out the fops structure,
call memset() in the INIT block of perl_fuse_main().