Add a note saying that table and database names can contain only alphanumeric characters and underscore
Fix size of text between <code>
Fix typo -- ROTS by @mglukhovsky
Merge branch 'v1.6.x' into next
Remove unnecessary UNUSED macro that cause warnings in clang 3.3

Review 644 by @srh
Renamed deletable_t::get() to deletable_t::get_copy()
and use deletable_t::get_ref() more often.
Merge branch 'next' into grey_issue_193