Change <span class="output">…</span> to <samp>…</samp>

Closes #277
:lt, :gt selectors: update to include -index

Closes #276
$.Callbacks: change an example to avoid confusion

No ticket.
Deferred methods: Update arg types for progress, reject, resolve

cf. http://forum.jquery.com/topic/confusion-of-anything-vs-object-in-documentation