Fix some issues with ACL handling:

Fix some issues with ACL handling:
  * ACL storage is no longer erased before a group of entries are added.
  * ACL text creation no longer tries to skip over non-existent text.
  * UTF8 encoder no longer blows up on invalid wide characters.
  * Fixed ACL state management for default ACLs.
Also, publicize function for obtaining text-format ACL in various
formats.  The interface is now extensible through a "flags" argument
that allows you to select a variant format.