Various small fixes/enhancements/changes

Currently:
* Bugfixes
  * Fixed [issue with canonical links](http://wordpress.org/support/topic/serious-canonical-issue-with-paginated-posts) on last page of paginated posts - props [maxbugfiy](http://wordpress.org/support/profile/maxbuxfiy)
  * Fixed bug in shortcode removal from meta description as reported by [professor44](http://profiles.wordpress.org/professor44/) in issue #83.
  * Fixed bug preventing saving of taxonomy meta data on first try - issue #88. 
  * Fixed small (potential) issue in wpseo_title_test().
  * Fixed bug where RSS excerpt would be double wrapped in `<p>` tags as reported by [mikeprince](http://profiles.wordpress.org/mikeprince) in issue #96.

* Enhancements
  * Added 'wpseo_breadcrumb_single_link_with_sep' filter which allows users to filter a complete breadcrumb element including the separator, as discussed in [this forum thread](http://wordpress.org/support/topic/remove-current-post-title-from-breadcrumbs)


But I kind of expect this pull request to gain some more before you're back from your holidays ;-)

(Updating this list as I go along)