MRBS 1.7.2 release

Files at https://p.sf.net/mrbs/mrbs172

This is a bugfix release of MRBS.

Changes since MRBS 1.7.1:

• Updated MySQL text encoding to utf8mb4, to allow use of later versions of Unicode,
  allowing for characters like emojis.
• Added CAS session/authentication scheme.
• 'php' session scheme updated to store sessions in the MRBS database.
• Added 'last login' field for 'db' authentication scheme.
• Plus quite a few other bug fixes/improvements.

See NEWS or ChangeLog in the release for more details.

Enjoy!

John Beranek