#517814 by jmstacey, justinrandell, pwolanin, drewish, Jody Lynn, aaron, dopry, and c960657: Converted File API to stream wrappers, for enhanced private/public file handling, and the ability to reference other storage mechanisms such as s3:// and flicker://.

- Patch #493466 by arianek, jhodgdon: documentation for file_save_upload inaccurately describes a parameter.

- Patch #227232 by dopry, c960657, jmstacey, pwolanin, aaron, drewish: added initial support for PHP file wrappers.

- Patch #520664 by rfay, quicksketch: file_get_mimetype() should not be case-sensitive. Comes with more and better tests.

- Patch #473652 by Damien Tournoud, catch: removed unneeded loop from file_get_mimetype() and further clean-up.

  times (such as crop, scale, then desaturate) without quality loss, we need to
  pass images by their raw GD (or other library) resources rather than re-opening
  the same image repeatedly, which causes wasted processing and loss of quality when
  using JPEG images.  This patch reworks the image toolkits, adds some new image
  manipulations and adds some impressive SimpleTests.

#330983 by recidive and boombatower: Rename users/users_roles tables to user/user_role for consistency.

#88264 by Rob Loach and kscheirer: Make variable_get()'s defaultparameter default to NULL so that NULLs do not need to be specified.

#30520 follow-up by Dave Reid: Fix error message about upload when not uploading a file (with tests, so we don't break it again).

- Patch #341910 by Josh Waihi, drewish et al: file_space_used() was not properly checking bitmapped status values. Added unit tests too.

- Patch #74645 by drewish, roychri et al: modify file_scan_directory to use a regex for the nomask (and code clean-up).