9.3 release notes:  update streaming replication speedups

Andres Freund
9.3 release notes:  apply fixes suggested by Alvaro
Mention in docs that you can create SP-GiST indexes on range types.

This is new in 9.3devel.
9.3 release notes:  adjustments per Alvaro and Robert
9.3 release notes: add diacritics

Alvaro Herrera
Remove prototype for cube(text) function that doesn't exist anymore.

Adrian Schreyer