Use REGISTRY SHARES instead of USER SHARES
+ These are a lot more configurable (more possibility to customize the share).
+ Remove the 'acl' option and replace it with 'writeable' instead.
+ On some machines, there is a "global" share. This isn't really a share,
  but the possibility to modify global options. So first get a line of
  _real_ shares using 'net conf listshares' and _then_ cyckle through
  them retrieving info with 'net conf showshare <share>'.
+ Add an example on how to modify a share after ZFS share and what man
  pages to use for more info.
Speedups (less share retreivals) and make sure the 'net' command is executable.
* Since smb_shares is global, we only retreive shares if it's NULL
  in smb_retrieve_shares(). It should limit the number of times we
  fork() and read shares (which takes time).
* If the net command don't exist (is executable), don't even register
  the smb fstype in libshare_smb_init().
* access() fix - check if NET_CMD_PATH is _executable_ not just 'exists'.