Make xarrayref() and xhashref() return empty lists ()

In list context returning an undef $ref is still a single 'undef', as
opposed to being an empty .... nothing.
Set version to 0.0.30
Release version 0.0.30 (2014-09-26)
Unset release date
Start development on version 0.0.31_1
Do not rollback or release unless inside a transaction
New db->xvals() and sth->vals() methods
Add LIKE/NOT LIKE support in hashrefs
Update Changes file
Release version 0.0.31_1 (2014-10-29)
Unset release date
Start development on version 0.0.32
Release version 0.0.32 (2014-10-30)
Unset release date
Start development on version 0.0.33_1
Don't need headers for changes that didn't happen