.keypress(): Fix info re difference from keydown

Closes #278
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
1.9.1-6
addclass: Fix error in expected outcome of an example.

Closes #273
Add .data(obj) example
.data(): Fix link to W3C HTML5 spec for data-* attrs

Closes #269
$.ajax(), .ajaxError(): Note re x-domain script/JSONP.

Closes #37
jQuery.type(): correct terminology, add "boxed" examples

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
:root selector: Remove stray arg from copy/pasta
1.9.1-7
jQuery.type(): <li> -> </li>
1.9.1-8
jQuery.browser. Make abundantly clear that jQuery.browser is removed as of jQuery 1.9.

Closes #283
Fixing typo in offset doc
Added CONTRIBUTING.md.
CONTRIBUTING: Added link to #jquery-content.
Fix a few entries with multiple return types:

* .get(), .prop(), and .val()
* Closes #291