Post Plugins Updated

Similar Posts, Random Posts, Recent Posts, and Recent Comments have all been updated. One or two bugs in parameter handling have been fixed, certain parameters can now be blank where appropriate, or be more complex than before, e.g., 'before_title=<li class="item">'.

Excerpts can now be trimmed down to stop them ending in mid-word. They can be cut back to a word or a sentence. NB excerpt_length is now counted in characters and not words as previously.