Make yourls_add_option() return something. Also, phpdocs.
(cherry picked from commit 7466a7eede079380342f39cb7992e8992c2ea7c9)
Sync yourls_is_serialized() with its WP counterpart. Also, phpdoc.
(cherry picked from commit d5ac2cc16da8632b983f1e0dea7348fafea48c42)
Also delete option from cache
(cherry picked from commit 93837dc0fdebf2fffad8de596a17d9e29ba4aba7)
Use clone to break object refs. Don't ask.

Stolen from people smarter than me:
- http://core.trac.wordpress.org/changeset/9740
- http://core.trac.wordpress.org/changeset/14777
- http://core.trac.wordpress.org/ticket/13480
(cherry picked from commit 09b989d375bac65e692277f61a84fede2fb04ae3)
Actually use values we escape. Duh.
(cherry picked from commit bdb51d94369d531ade1c74ebb987f2a36758aa00)
Comments about that mysterious clone because I'll never remember that in 3 months
(cherry picked from commit 1fa67f523de93068b3713d41a187316b61d62e2b)